an element x atomic number 16 reacts with an element Y atomic number 20 to form a compound
i) position of the elements in the modern periodic table
ii) what type of bond will be formed between them ? give reason
iii) write the chemical formula of the compound ​

Answer:

D. NH3

Explanation:

Hydrogen bonding exists only between hydrogen atoms, and is one of the strongest intramolecular forces. So you eliminate your choices down to B and D. HCl can't form Hydrogen bonding because of electron density and electronegativity but NH3 can, so your answer would be D.

Answer:

The correct option is desertification

Explanation:

Deforestation is the deliberate act of pulling down trees to provide a clear land for space or to make use of the trees for other purposes  such as grazing, farming, timber fire wood, building and constructions, urban utilization, access roads, expansion, development of infrastructures, grazing of cattle and mining

The effects of deforestation includes climate change, flooding, increase in the proportion of green house gases in the atmosphere, soil erosion and desertification.

A negative effect of deforestation is desertification.

Deforestation refers to the cutting down of trees. There are many reasons why people may cut down trees. One of the popular reasons why people cut down trees is to obtain timber which is used for construction and as fuel.

An important consequence of the felling of trees also called deforestation is that a once fertile land may gradually be turned into a desert area. This is known as desertification.

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Explanation:

I think Low melting point

because NaCl (salt has mp 801 degC)

Water has mp 0 degC

The required  complete ionic equation of the reaction

Pb(NO3)2+2KI---->PbI2+2KNO3   is   Pb2+(aq) + 2 I−(aq) → PbI2(s)

A chemical equation in which the electrolytes in aqueous solution are expressed as dissociated ions.

Spectator ions in above equation are as follows- K +and NO3−

Define spectator ions.

Ions that are not involved in the actual chemical reaction are called spectator ions.

Net ionic equation of given reaction isPb⁺²+2I ⁻¹⟶PbI₂It shows only the ions which involves in the chemical reaction.

Therefore, K⁺ and NO3⁻ are spectator ions.

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Answer: The chemical formula for lead (II) iodide is [tex]PbI_2[/tex]

Explanation:

Lead (II) iodide is a ionic compound because it are formed by transference of electrons between metals and non metals.The bond formed between a metal and a non-metal is always ionic in nature.

For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.

The nomenclature of ionic compounds is given by:

1. Positive is written first followed by the oxidation state of metal in roman numerals in square brackets.

2. The negative ion is written next and a suffix is added at the end of the negative ion. The suffix written is '-ide'.

The chemical formula for lead (II) iodide is [tex]PbI_2[/tex]

Answer:

[tex]L_{\text{fusion}[/tex] is latent heat of fusion.

Explanation:

[tex]Q=mL_{\text{fusion}}[/tex]

Here,

m is mass of substance

[tex]L_{\text{fusion}[/tex] is latent heat of fusion.

Answer:

172.385 g/mol

Explanation:

Magnesium Tartrate is C4H4MgO6

C - 12.01 g/mol

H - 1.01 g/mol

Mg - 24.305 g/mol

O - 16.00 g/mol

12.01(4) + 1.01(4) + 24.305 + 16(6) = 172.385 g/mol

Answer:

172.38

Explanation:

[tex]C_4H_4MgO_6\\C=12.01\\H=1.01\\Mg=24.30\\O=16.00\\\\4(12.01)+4(1.01)+24.30+6(16.00)\\48.04+4.04+24.30+96\\=172.38[/tex]

C = 12.01

H=1.01

Mg=24.30

O =16.00

4(12.01)+4(1.01)+24.30+6(16.00)

48.04 +4.04+24.30+96

=172.38

The correct answer is C. Climate change

Explanation:

Long-term environmental changes occur as major events affect the environment and ecosystems indefinitely. These events differ from short-term environmental changes because the effect of short-term environmental changes is mainly temporary. Also, long-term changes are usually gradual.

Climate change is an example of long-term environmental changes because this implies indefinite and major changes in weather patterns and ecosystems. For example, it is believed climate change will decrease the amount of ice in Earth, change sea level, and lead to the extinction of dozens of species. This does not occur with events such as el niño or a small asteroid impact that affect the environment for a short time and do not imply major changes.

Answer:

it is c) climate change

Explanation:

i just took the quiz

hope this helps!!!   :D

Answer:

40.47 g Al

Explanation:

In 1 mol of Al, there are 26.98 grams of Al, so Al is 26.98 g/mol.

Simply multiply 1.5 by 26.98 to get your answer.

Answer:

[tex]1.63 \times {10}^{24} [/tex]

one atom of an element = 6.02 \times {10}^{23} atom

The mass of one atom of sulphur = 32g

The mass of one atom of aluminium = 27g

so one atom of aluminium = 6.02 \times {10}^{23}

27g of AL = 6.02 \times {10}^{23} atom

2.70g of AL = X atoms

Then you cross multiply ........

and get the answer

.

Answer:

Molarity of the glucose solution = 2.72 mol/L

Explanation:

Molality of a solution is defined as the number of moles of solute per kilogram of solvent.

Therefore , a 2.27 molal solution of glucose contains 2.27 moles of glucose in 1 Kg of solvent

Density of solution = 1.20 g/mL

The volume occupied by 1 Kg or 1000 g solution = mass/density

Volume of 1000 g solution = 1000 g/1.20 g/ml = 833.3 mL

Number of moles of glucose present in the solution = 2.27 moles

Molarity = number of moles / volume(L)

volume of solution in litres = 883.3/1000 = 0.8333 L

Molarity = 2.27 moles /0.8333 l = 2.72 mol/L

Therefore, molarity of the glucose solution = 2.72 mol/L

The molarity of the glucose in the solution has been 2.72 mol/L.

Molality can be defined as the moles of the solute per kg of solvent.

The molality of glucose solution = 2.27 m

2.27 moles of glucose in 1000 grams of water.

Density has been the mass per unit volume. The density can be expressed as:

Density = [tex]\rm \dfrac{Mass}{Volume}[/tex]

The density of the given glucose solution = 1.20 g/ml

The volume of 1000 grams of water has been:

Volume = [tex]\rm \dfrac{Mass}{Density}[/tex]

Volume of 1000 grams water = [tex]\rm \dfrac{1000\;g}{1.20\;g/ml}[/tex]

Volume of 1000 g water = 833.3 ml

The molarity can be defined as the mass of solute per liter of the solution.

Molarity = [tex]\rm moles\;\times\;\dfrac{1000}{Volume\;(ml)}[/tex] ......(i)

The moles of glucose in the 833.3 ml solution have been 2.27 mol.

Substituting the values in equation (i):

Molarity = 2.27 mol [tex]\rm \times\;\dfrac{1000}{833.3\;ml}[/tex]

Molarity = 2.72 mol/L.

The molarity of the glucose in the solution has been 2.72 mol/L.

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Answer:

amoeba is the unicellular organism which can be seen by only microscope but not with our nacked eyes

Answer:

An amoeba often called an amoeboid, is a type of cell or unicellular organism which has the ability to alter its shape, primarily by extending and retracting pseudopods Amoebae do not form a single taxonomic group; instead, they are found in every major lineage of eukaryotic organisms. Amoeboid cells occur not only among the protozoa, but also in fungi, algae, and animals.

name of parts of ameoba

3 parts – the cytoplasm, plasma membrane and the nucleus. The cytoplasm can be differentiated into 2 layers – the outer ectoplasm and the inner endoplasm. The plasma membrane is a very thin, double-layered membrane composed of protein and lipid molecule

i hope this will help you

Answer:

It’s D

Explanation:

Answer:

D Rocks change from one type to another in a specific order.

Explanation:

Answer:

A chemical element

Explanation:

A chemical element consists of only one type of atom.

Answer:

A is the answer.

Explanation:

The sound wave is a longitudinal wave which travels in the form of compression and rarefaction . The point where the particles are closer to each other is called compression and the point where the particles are far apart from each other is called rarefaction.

Answer:

Amplitude

Explanation:

Amplitude describes the displacement of the medium's particles. The higher the amplitude, the more dense it is, and the lower the amplitude, the less dense it is.

Pitch is incorrect because it describes the sound

Volume is incorrect because it describes the sound.

Wavelength is incorrect because it describes the distance between a period of a wave.

Answer:

there is an increase by 0.18 V in the cell voltage.

Explanation:

The given equation of the reaction can be well written as

[tex]2AgCl_{(s)} + Zn _{(s)} \to 2Ag_{(s)} + 2 Cl^- _{(aq)}+ Zn^{2+}_{(aq)}[/tex]

By application of Nernst Equation ; we have the expression

[tex]E_{cell} = E^0- \dfrac{0,059}{n}log (\dfrac{[product]}{[reactant]})[/tex]

here in the above equation;

n = number of electrons transferred in the equation of the reaction

n = 2

Also;

[tex]E^0 = E_{cathode} - E_{anode}[/tex]

[tex]E^0 = E_{Ag^+/Ag} - E_{Zn^+/Zn}[/tex]

[tex]E^0 = +(0.80 \ V) - (-0..76 \ V)[/tex]

[tex]E^0 = (0.80 \ V +0..76 \ V)[/tex]

[tex]E^0 = 1.56 \ V[/tex]

If the zinc ion concentration is kept constant at 1 M; we have:

[tex]E_{cell} = E^0- \dfrac{0.059}{n}log (\dfrac{[product]}{[reactant]})[/tex]

[tex]E_{cell} = 1.56 - \dfrac{0.059}{2}log ({[Zn^{2+} ]}{[Cl^{2-}]})[/tex]

[tex]E_{cell} = 1.56 - \dfrac{0.059}{2}log (1)[/tex]

Since log(1) = 0

Therefore;

[tex]E_{cell} = 1.56\ V[/tex]

When the chlorine ion concentration is decreased from 1 M to 0.001 M; we have;

[tex]E_{cell} = E^0- \dfrac{0.059}{n}log (\dfrac{[product]}{[reactant]})[/tex]

[tex]E_{cell} = 1.56 - \dfrac{0.059}{2}log ({[Zn^{2+} ]}{[Cl^{2-}]})[/tex]

[tex]E_{cell} = 1.56 - \dfrac{0.059}{2}log ({[1*0.001^2}]})[/tex]

[tex]E_{cell} = 1.56 - 0.0295 \ * \ log ({[1*10^{-6}}]})[/tex]

[tex]E_{cell} = + 1.737 \ V[/tex]

The change in voltage = [tex]E_{cell} - E^0[/tex]

=( 1.737 - 1.56 )V

= 0.177 V

≅ 0.18 V

Thus; from the following observation; there is an increase by 0.18 V in the cell voltage.

The voltage of the cell increased by 0.18 V.

The equation of the reaction is; 2AgCl(s) + Zn(s) → 2Ag(s) + 2Cl– + Zn2+

We know that;

E°cell = 1.36 - (-0.76) = 2.12 V

If the cells are both at 1M concentration the Ecell = E°cell = 2.12 V

When the concentration of Cl- decreased from 1 M to 0.001 M

Ecell =  E°cell - 0.0592/n log Q

Substituting values;

Ecell = 2.12 V -  0.0592/2 log (1 × (0.001)^2)

Ecell = 2.298 V

Increase in voltage = 2.298 V - 2.12 V = 0.18 V

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Answer:

Heating Fan is 75.33% efficient.

Explanation:

As it is mentioned that the given fan is a HEATING FAN, it means the it is used for provided heat (thermal energy) to the surrounding. Hence, its efficiency depends upon how much heat/thermal energy is provides.

We can state that.

Total Energy provided = 150 J

Useful Energy = 113 J

Wasted Energy = 37 J

The efficiency of the heating fan can be given by following formula:

Efficiency = ( Useful Energy / Total Energy ) × 100

Efficiency = ( 113 J / 150 J) × 100

Efficiency = (0.7533)× 100

Efficiency = 75.33%

Answer: Payback time = 0.0075

Explanation: Since payback time is calculated as:

payback time = [tex]\frac{installation cost}{annual savings}[/tex]

First determine the installation cost:

100 mm thick insulation covers 8.3 m². Then 300 mm covers 24.9 m².

To cover 8.3m² costs £20. Then, the cost to cover 24.9 m² is:

cost = [tex]\frac{20*24.9}{8.3}[/tex]

cost = £60

The cost of putting the insulation is £120, so the total cost is:

total cost = £60 + £120

total cost = £180

Savings per year per 100 mm thick is £80. For 300 mm, the value of annual savings is:

savings = [tex]\frac{300*80}{100}[/tex]

savings = 240

payback time = [tex]\frac{installation cost}{annual savings}[/tex]

payback time = [tex]\frac{180}{240}[/tex]

payback time = 0.75

The mole is used to measure small particles like atoms and molecules.  The 4 moles of silver is equivalent to [tex]\bold{2.408 x 10^2^4 }[/tex] atoms.

Given here,

The number of atoms

[tex]\bold{2.408 x 10^2^4 }[/tex]

Number of moles = ?

1 mol of substance = [tex]\bold{ 6.02 x10^2^3}[/tex]

Hence,

moles of silver,

[tex]\bold {= \dfrac {2.408 x 10^2^4 } { 6.02 x10^2^3} }}\\\\\bold {= 4 mol}[/tex]

Therefore, the 4 moles of silver is equivalent to [tex]\bold{2.408 x 10^2^4 }[/tex] atoms.

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Answer:

[tex]\large \boxed{\text{104 kPa}}[/tex]

Explanation:

To solve this problem, we can use the Combined Gas Laws:

[tex]\dfrac{p_{1}V_{1} }{n_{1}T_{1}} = \dfrac{p_{2}V_{2} }{n_{2}T_{2}}[/tex]

Data:

p₁ = 748 kPa;  V₁ =   273 m³;  n₁ = n₁;  T₁ =  525 K

p₂ = ?;             V₂ = 1100. m³; n₂ =  n₁; T₂ =  293 K

Calculations:

[tex]\begin{array}{rcl}\dfrac{p_{1}V_{1}}{n_{1} T_{1}} & = & \dfrac{p_{2}V_{2}}{n_{2} T_{2}}\\\\\dfrac{\text{748 kPa}\times \text{273 m}^{3}}{n _{1}\times \text{525 K}} & = &\dfrac{p_{2}\times \text{1100. m}^{3}}{n _{1}\times \text{293 K}}\\\\\text{390.0 kPa} & = &3.754{p_{2}}\\p_{2} & = & \dfrac{\text{390.0 kPa}}{3.754}\\\\ & = & \textbf{104 kPa} \\\end{array}\\\text{The new pressure is $\large \boxed{\textbf{104 kPa}}$}[/tex]

Answer:

In First compound the longest chain contains 7 C atoms.

In the Second compound the longest chain contains 9 C atoms.

In the Third compound the longest chin contains 7C atoms.

Explanation:

In first compound the longest chain contains 7 carbon atoms.In the second compound the longest chain contains 9 carbon atoms.In the third compound the longest chin contains 7 carbon atoms.

An atom is defined as the smallest unit of matter which forms an element. Every form of matter whether solid,liquid , gas consists of atoms . Each atom has a nucleus which is composed of protons and neutrons and shells in which the electrons revolve.

The protons are positively charged and neutrons are neutral and hence the nucleus is positively charged. The electrons which revolve around the nucleus are negatively charged and hence the atom as a whole is neutral and stable due to presence of oppositely charged particles.

Atoms of the same element are similar as they have number of sub- atomic particles which on combination do not alter the chemical properties of the substances.

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Answer:

smaller volume ⇒ Crowded particles ⇒ More collisions  ⇒ Higher pressure

Explanation:

Smaller the volume , more crowed the particles . Then the particles will have rapid collisions so the free mean path is decreased , hence the pressure will be increased as follows

[tex]P=\frac{K_bT}{\sqrt{2}\pi d^2\lambda }[/tex]

where λ is mean free path , P is pressure .

The sequence the represent the relationship between pressure and volume of an ideal gas is: smaller volume right arrow Crowded particles right arrow More collisions right arrow Higher pressure

The kinetic molecular theory made five postulates which are used to explain the behaviour of gases.

From the postulates, he uses the kinetic molecular theory to explain Boyle's Law because the majority of a gas's volume in space is usually empty and may be compressed.

So, when a gas is compressed without affecting its temperature, the average kinetic energy of the gas particles remains constant. The particles continue to flow at the same rate, but the container has reduced.

As a result, the particles go from one end of the container to another in less time. This suggests they're hitting the barriers (collision) more frequently. Each and every increase in the frequency of collisions with the walls, thus, results in an increase in the gas's pressure.

Hence, as the volume of a gas decreases, the pressure of the gas increases.

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Answer:

the molarity of cobalt(II) fluoride in the resulting solution is = 0.137  M

Explanation:

Given that :

a student dissolves 6.64 g of CoF₂  into 500 mL of water

volume of the solution(water) = 500 mL = 0.50 L

The standard  molar mass of CoF₂ is 96.93 g/mol

number of moles of CoF₂ = mass of CoF₂/molar mass of CoF₂

number of moles of CoF₂ = 6.64 g/96.93 g/mol

number of moles of CoF₂ = 0.0685 mol

The molarity of any given substance is known to be as the number of moles of solute dissolved in one litre of solution.

Thus ;

Molarity of  cobalt(II) fluoride CoF₂ in the resulting solution is = number of moles / Volume in (L)

Molarity of  cobalt(II) fluoride CoF₂  = 0.0685 mol/ 0.50 L

= 0.137  M

Thus ; the molarity of cobalt(II) fluoride in the resulting solution is = 0.137  M

Answer:

B.

Explanation:

A weak bond forms from a smaller change in energy compared to a strong bond.

Answer:

The correct answer to the following question will be Option A (Microwaves).

Explanation:

The other given choices are not related to the given circumstances. So that option A seems to be the appropriate one.

Answer:

its a

Explanation:

Answer:

2.01 A

Explanation:

Para esta pregunta debemos empezar por la semi-reaccion del plomo:

[tex]Pb^+^2~_(_a_q_)~+~2e^-~->~Pb_(_s_)[/tex]

Se intercambian dos electrones en la semi-reacción del plomo. Si tenemos en cuenta la ecuación:

[tex]n=\frac{I*t}{z*F}[/tex]

Donde:

n= Moles depositados

I= Intensidad de corriente (en Amperios)

z= Numero de electrones intercambiados

F= Constante de faraday = 96484 C/mol

t=tiempo (en segundos)

Que conocemos de esta ecuación?

Los moles (se pueden calcular a partir de la masa atómica del plomo, 207.2 g/mol)

[tex]2.6~g~Pb\frac{1~mol~Pb}{207.2~g~Pb}=0.0125~mol~Pb[/tex]

El tiempo (hay que convertirlo a segundos):

[tex]20~min\frac{60~s}{1~min}=1200~s[/tex]

Z (Numero de electrones)

De acuerdo a la semi-reacción son intercambiados 2 electrones.

Por lo tanto podemos resolver para "I":

[tex]I=\frac{n*z*F}{t}=\frac{0.0125~mol*2*96484\frac{C}{mol}}{1200~s}[/tex]

[tex]I~=~2.01~\frac{C}{s}=2.01~A[/tex]

Espero que sea de ayuda!

Answer:

The biological sample that pregnancy tests use to detect pregnancy is urine

Answer:

yes

Explanation:

the urine in the the tester will find hormones to determine if pregnant or not

Answer:

Kinetic energy of boy just before hitting the ground is [tex]\approx[/tex]1000 J.

Speed of boy just before hitting the ground is 7.67 m/s

or 17.16 mi/hr.

Explanation:

Given that:

Mass of boy = 75lb = 34 kg

Height, h = 10ft = 3m

To find:

Kinetic energy of boy when he hits the ground.

As per law of conservation of energy The potential energy gets converted to kinetic energy.

[tex]\therefore[/tex] Kinetic energy at the time boy hits the ground = Initial potential energy of the boy when he was at the Height 'h'

The formula for potential energy is given as:

[tex]PE = mgh[/tex]

Where m is the mass

g is the acceleration due to gravity, g = 9.8 [tex]m/s^2[/tex]

h is the height of object

Putting all the values:

PE = [tex]34 \times 9.8 \times 3 \approx 1000\ J[/tex]

Hence, Kinetic energy is [tex]\approx[/tex]1000 J.

Formula for Kinetic energy is:

[tex]KE = \dfrac{1}{2}mv^2[/tex]

where m is the mass and

v is the speed

Putting the values and finding v:

[tex]1000 = \dfrac{1}{2}\times 34 \times v^2\\\Rightarrow v^2 = 58.82\\\Rightarrow v = 7.67\ m/s[/tex]

Given that:

1 m = 1.094 yd and 1 mi = 1760 yd

[tex]\Rightarrow 1609\ m = 1\ mi[/tex]

Converting 7.67 m/s to miles/hour:

[tex]\dfrac{7.67 \times 3600}{1609}=17.16\ mi/h[/tex]

Answer:Drinking straw

Explanation: my quiz said so

The object that represents the best model of one of the phloem cells is the drinking straw.

Phloem may be defined as a type of vascular tissue in plants that significantly conducts the passage of sugars and other metabolic products from the leaves to the roots. This mediates the migration of sugar which is synthesized in the leaves during photosynthesis.

Apart from this, the phloem also regulates the movement of nutrients from the roots to the upper part of the body. This function of phloem cells shares homology with the object known as a drinking straw that mediates the transport of any fluid in both directions.

Therefore, a drinking straw is an object that represents the best model of one of the phloem cells.

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