Scientists did not know about cells before the 1600s because the
microscope had not been invented yet. *
O True
False

Answer:

Extreme heat

Explanation:

Because when matter is heated up The molecules move faster.

Answer:

I think it's extreme heat

Answer:

Zn(NO3)2(aq) + 2NaOH(aq)  —> Zn(OH)2 (s) + 2NaNO3(aq)

Zn++ + 2NO3-  + 2Na+ + 2OH- —> Zn(OH)2 + 2Na+ + 2NO3-

Zn++ 2OH- —> Zn(OH)2

Na+, NO3-

Explanation:

Zn(NO3)2(aq) + 2NaOH(aq)  —> Zn(OH)2 (s) + 2NaNO3(aq)

Answer:

yes, the cells in the liguid is all congrating together.

Explanation:

Answer:

I think the answer is b

Explanation:

the paragraph states, that it is an experiment to see if there is any oxygen in the water

Answer: (2) releases 2260 J/g of heat energy

Explanation:

Latent heat of vaporization is the amount of heat required to convert 1 mole of liquid to gas at atmospheric pressure.

Latent heat of condensation is energy released when 1 mole of  vapor condenses to form liquid droplets.

The temperature does not change during this process, so heat released goes into changing the state of the substance, thus it is called latent which means hidden. The energy released in this process is same in magnitude as latent heat of vaporization. The heat of condensation of water vapour is about 2,260 J/g.

Phase transition refers to the changes in the states of matter between gas, liquids, and solids.

The correct answer is:

Option 2. releases 2260 J/g of heat energy

The process can be explained as:

1. Condensation is the process of conversion of water vapor into the liquid state.

2. Latent heat of vaporization is defined as the amount of heat required for 1 mole of liquid to convert into a gaseous phase at atmospheric pressure.

3. The change in the temperature does not occur during the condensation, and the heat required for the phase transition is latent heat. The heat of condensation of water vapor is 2,260 J/g.

Thus, the correct answer is Option 2.

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Answer:

H+ (aq)  +    ClO- (aq)  --->   HClO(aq)  

Explanation:

The net ionic reaction equation is a chemical equation that explicitly shows only the particular ions that undergo a chemical change in the course of a given reaction.

In this particular reaction, the molecular reaction equation is shown as follows;

HNO3(aq) + NaOCl(aq) -----------> NaNO3(aq) + HOCl(aq)

Ionically;

H+ (aq)  +    ClO- (aq)  --->   HClO(aq)

Answer:

[tex]M_{C_9H_{13}NO_3}=183.23g/mol[/tex]

Explanation:

Hello!

In this case, since the molar mass of a chemical compound is computed by averaging the atomic mass of each element in the molecule and the amount of atoms; which in this case there are 9 carbon atoms, 13 hydrogen atoms, 1 nitrogen atom and 3 oxygen atoms; thus, we compute the average as shown below:

[tex]M_{C_9H_{13}NO_3}=m_C*9+m_H*13+m_N+m_O*3[/tex]

Now, we plug in the atomic masses to obtain:

[tex]M_{C_9H_{13}NO_3}=12.01*9+1.01*13+14.01+16.00*3\\\\M_{C_9H_{13}NO_3}=183.23g/mol[/tex]

Best regards!

Answer:

the answer is B:) have a good day

Answer:

ionic solids

Explanation:

Ionic solids are a regular pattern of cations and anions that arrange themselves into a continuous solid network.

NaCl is composed of sodium ions and chloride ions that are held together by Coulumbic attractive forces to form a large crystal structure.

Such ionic solids have a very high melting point and do not conduct electricity in the sold state. However, the molten substance or a solution of the substance conducts electricity.

Answer:

The mass of 8.50 × 10²² NH₃ molecules is ≈ 1.84 g.

One mole of a molecule contains 6.02 × 10²³ molecules. The mass of  8.50 × 10²² molecules of NH₃ is 2.39 g.

Ammonia is an inorganic compound formed by hydrogen and nitrogen. Ammonia exists in gaseous state.

One mole of every element or compound contains 6.02 × 10²³ molecules. This number is called Avogadro number. The molar mass of ammonia is 17 g/l

It is given that the number of molecules of ammonia here, is 8.50 × 10²².

The no.of moles of ammonia = 8.50 × 10²²/ 6.02 × 10²³

                                                = 0.141 moles.

If one mole ammonia is 17 g/l, the mass of 0.141 moles of NH₃ is calculated as follows: 0.141 × 17 = 2.39 g. Hence the mass of NH3 which contains 8.50 × 10²² molecules is 2.39 g.

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Answer:

V₂ =1.99 L

Explanation:

Given data:

Initial volume = 1.8 L

Initial temperature = 28°C (28+273.15 K= 301.15 k)

Initial pressure = 102 KPa

Final volume = ?

Final pressure = 85 KPa

Final temperature = 4°C (4+ 273.15 K = 277.15 K)

Solution:

Formula:  

P₁V₁/T₁ = P₂V₂/T₂  

P₁ = Initial pressure

V₁ = Initial volume

T₁ = Initial temperature

P₂ = Final pressure

V₂ = Final volume

T₂ = Final temperature

V₂ = 102 KPa × 1.8 L × 277.15 K / 301.15 K × 85 KPa

V₂ = 50884.74 KPa .L. K / 25597.75 K.KPa

V₂ =1.99 L

Answer:

Tetrahedral

Explanation:

SF2H2 is a derivative of the sulfuranes (SL4) compounds. The quantum mechanics of these sulfuranes is quite complicated.

Simply, they consist of ten electrons around the sulphur central atom one of which is a lone pair. The electronegativity of fluorine plays a key role in the structure and molecular geometry of SF2H2.

The molecule is found to be tetrahedral in shape by quantum mechanical calculations.

Answer:

nitrogen

Explanation:

The atmosphere contains many gases, most in small amounts, including some pollutants and greenhouse gases. The most abundant gas in the atmosphere is nitrogen, with oxygen second. Argon, an inert gas, is the third most abundant gas in the atmosphere. Why do I care?

nitrogen is the most abundant gas in the atmosphere

Answer:

0.0457M is molarity of nitrate anion in the solution.

Explanation:

Molarity is defined as the ratio between moles of solute (In this case, nitrate ion) and liters of solution (The total volume of the solution is 300.0mL = 0.300L).

Thus, we need to convert mass of Lead(II) nitrate to moles using its molar mass (Molar mass Pb(NO₃)₂: 331.2 g/mol). Moles of Pb(NO₃)₂ = 1/2 Moles of NO₃⁻:

Moles Pb(NO₃)₂ and moles of NO₃⁻:

2.27g * (1mol / 331.2g) = 0.006854 moles Pb(NO₃)₂ * (2moles NO₃⁻ / 1mol Pb(NO₃)₂) = 0.0137moles NO₃⁻

Molarity is:

0.0137 moles NO₃⁻ / 0.300L =

Answer:

44Kj

Explanation:

These are the equations for the reaction described in the question,

Vaporization which can be defined as transition of substance from liquid phase to vapor

H2(g)+ 1/2 O2(g) ------>H2O(g). Δ H

-241.8kj -------eqn(1)

H2(g)+ 1/2 O2(g) ------>H2O(l).

Δ H =285.8kj ---------eqn(2)

But from the second equation we can see that it moves from gas to liquid, we we rewrite the equation for vaporization of water as

H2O(l) ------>>H2O(g)---------------eqn(3)

But the equation from eqn(2) the eqn does go with vaporization so we can re- write as

H2O ------> H2(g)+ 1/2 O2(g)

Δ H= 285.8kj ---------------eqn(4)

To find Delta h of the vaporization of water at these conditions, we sum up eqn(1) and eqn(4)

Δ H=285.8kj +(-241.8kj)= 44kj

Answer:

15 neutrons

Explanation:

Number of neutrons = atomic mass - number of protons.

So Neutrons = 28 - 13 protons

(Since atom is neutral, number of electrons = number of protons, which is how I get the 13 protons)

Neutrons = 15

Answer:

11

Explanation:

Moles of KOH = [tex]10^{-2}[/tex]

Volume of water = 10 liters

Concentration of KOH is given by

[tex][KOH]=\dfrac{10^{-2}}{10}\\\Rightarrow [KOH]=10^{-3}\ \text{M}[/tex]

[tex][KOH][/tex] is strong base so we have the following relation

[tex][KOH]=[OH^{-}]=10^{-3}\ \text{M}[/tex]

[tex]pOH=-\log [OH^{-}]=-\log10^{-3}[/tex]

[tex]\Rightarrow pH=14-3=11[/tex]

So, pH of the solution is 11

Answer: D

Explanation:

The personal data are transmitted using digital signals. The data might be stolen or accessed by hackers to go wrong with these transmissions. Therefore, option D is correct.

A digital signal is one that can only ever take on one of a few discrete values at any given time. It represents data as a sequence of discrete values.

A continuous signal that represents physical measurements is an analog signal. Digital modulation is used to create time-separated signals known as digital signals. Sine waves serve as its signal. The square waves serve as a marker.

It makes use of a continuous range of values to aid in the representation of data. Digital technologies are any techniques, systems, equipment, or resources that produce, store, or process data electronically.

Thus, option D is correct.

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Answer:

The transfer was essential to understand the mutation and the possibility of new, more resistant strains in microorganisms.

Explanation:

the transfer of microorganisms is based on the transfer of genetic data through conductive pathways that penetrate the membranes, called pili or genetic bridges.

These mutated genes with higher resistance are transmitted and resistance is generated in entire populations and even species.

Answer:

1) Mass =  890.96 g

2) Mass =  7.67 g

3) 507.65 ×10²³ atoms

Explanation:

1) Given data:

Number of moles of lead = 4.3×10⁻³ mol

Mass of lead = ?

Solution:

Mass = number of moles × molar mass

Molar mass of lead = 207.2 g/mol

by putting values,

Mass = 4.3×10⁻³ mol × 207.2 g/mol

Mass =  890.96 g

2) Given data:

Number of atoms of antimony = 3.8×10²² atoms

Mass of antimony = ?

Solution:

1 mole contain 6.022 ×10²³ atoms

3.8×10²² atoms × 1 mol / 6.022 ×10²³ atoms

0.63×10⁻¹ mol

0.063 mol

Mass:

Mass = number of moles × molar mass

Molar mass of lead = 121.76 g/mol

Mass = 0.063 mol ×  121.76 g/mol

Mass =  7.67 g

3) Given data:

Mass of tungsten = 15.5 Kg (15.5 kg × 1000 g/ 1kg = 15500 g)

Number of atoms = ?

Solution:

Number of moles of tungsten:

Number of moles = mass/molar mass

Number of moles = 15500 g / 183.84 g/mol

Number of moles = 84.3 mol

1 mole contain 6.022 ×10²³ atoms

84.3 mol  × 6.022 ×10²³ atoms / 1mol

507.65 ×10²³ atoms

Answer:

For example, when we bake a cake, it's a result of a mixture of eggs, flour, sugar, and other ingredients.  Any time two or more items are combined, a mixture is formed. Sometimes, the different parts of a mixture can be separated into individual entities. Other times, they're married for as long as they exist.

Explanation:

Answer:

Option C. 24 days / 4 grams

Explanation:

From the question given above, the following data were obtained:

Days Elapsed >>>> Mass Remaining

0 >>>>>>>>>>>>>>> 16

12 >>>>>>>>>>>>>>> 11

24 >>>>>>>>>>>>>>> 8

36 >>>>>>>>>>>>>>> 6

A. Determination of the half-life of Thorium-234.

To determine the half-life, it is important to know the definition of half life.

Half-life is defined as the time taken for a substance to reduce to half its original mass.

From the table given above, we can see that the original mass of the isotope is 16 g (i.e at 0 day). By day 24, the mass of the isotope is 8 g (i.e half the original mass). Thus, the half-life of the isotope is 24 days.

B. Determination of the mass of the isotope remaining after 2 half lives.

Original amount (N₀) = 16 g

Number of half-lives (n) = 2

Amount remaining (N) =?

N = 1/2ⁿ × N₀

N = 1/2² × 16

N = 1/4 × 16

N = 4 g

Thus, 4 g of the isotope is remaining after 2 half lives.

Summay:

Half-life = 24 days

Amount remaining after 2 half-lives = 4 g

Option C gives the correct answer to the question.

Answer:

See answer below

Explanation:

In this case, I will put the original photo of this exercise, because we are missing one data. The first picture is the original exercise.

Now, according to this, we need to make a serial dilution of CO(NO₃)₂. We don't know the volume of this solution, but we do know the total volume of the preparing solution (In the picture states that the total volume will be 10 mL).

So, we know the final volume of the solutions to be prepared, so, le'ts use the expression that will help us to solve this:

C₁V₁ = C₂V₂

Where:

C₁: Concentration of the given solution (stock)

V₁: volume required to prepare the dilluted solution

C₂; Concentration of the dilluted solution

V₂: Total volume of the dilluted solution.

Now that we know the expression to use and the meaning of each value, let's prepare the solutions:

To prepare 10 mL of 0.1 M using a 0.25 M, we will replace these values in the above expression; from there, we will solve for V₁, that value will tell us the required volume to prepare solution 2, and then, by difference we can calculate the volume of water:

Volume of water (Vw) =V₂ - V₁  

Now replacing the values:

0.25V₁ = 0.1 * 10

V₁ = 1/0.25 = 4 mL

This means that we need 4 mL of the stock to prepare the 0.1 M of dilluted solution, therefore, the volume of water required is:

Vw = 10 - 4

Using these same steps for the other two solutions we will get V1 and V2 for both of them. In this case, I will go straight to the procedure without further explanation because it's the same of this one.

For solution 2:

0.1V₁ = 0.05 * 10

V₁ = 0.5/0.1

Vw = 10 - 5

Finally for solution 3:

V₁ = 0.01 * 10 / 0.05

Vw = 10 - 2 mL

Hope this helps

Answer:

B

Explanation:

Answer:

C

Explanation:

Condensation

Answer:

C....... ...................

Answer:

66.5753 amu

Explanation:

From the question given above, the following data were obtained:

Isotope A (⁶⁵X):

Mass of A = 65.0457 amu

Abundance of A = 20.53%

Isotope B (⁶⁷X):

Mass of B = 66.9704 amu

Abundance of B = 79.47%

Atomic mass of X =?

The atomic mass of X can be obtained as follow:

Atomic mass = [(mass of A × A%)/100] + [(mass of B × B%)/100]

= [(65.0457 × 20.53)/100] + [(66.9704 × 79.47)/100]

= 13.3539 + 53.2214

= 66.5753 amu

Therefore, the atomic mass of X is 66.5753 amu.

Element X, with an atomic mass of 66.58 amu, has 2 naturally occurring isotopes, ⁶⁵X (65.0457 amu, 20.53%) and ⁶⁷X (66.9704 amu,  79.47%).

The average atomic mass (atomic mass) of an element is the sum of the masses of its isotopes, each multiplied by its natural abundance.

Element X has 2 isotopes:

We can calculate the average atomic mass of X using the following expression.

mX = m⁶⁵X × ab⁶⁵X + m⁶⁷X × ab⁶⁷X

mX = 65.0457 amu × 0.2053 + 66.9704 amu × 0.7947

mX = 66.58 amu

Element X, with an atomic mass of 66.58 amu, has 2 naturally occurring isotopes, ⁶⁵X (65.0457 amu, 20.53%) and ⁶⁷X (66.9704 amu,  79.47%).

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Answer:

Explanation:

1) Given data:

Number of moles of lead = 4.3×10⁻³ mol

Mass of lead = ?

Solution:

Mass = number of moles × molar mass

Molar mass of lead = 207.2 g/mol

Mass = 4.3×10⁻³ mol × 207.2 g/mol

Mass =  890.96 g

2) Given data:

Number of atoms of antimony = 3.8×10²² atoms

Mass of antimony = ?

Solution:

1 mole contain 6.022 ×10²³ atoms

3.8×10²² atoms × 1 mol / 6.022 ×10²³ atoms

0.63×10⁻¹ mol

0.063 mol

Mass = number of moles × molar mass

Molar mass of lead = 121.76 g/mol

Mass = 0.063 mol ×  121.76 g/mol

Mass =  7.67 g

3) Given data:

Mass of tungsten = 15.5 Kg (15.5 kg × 1000 g/ 1kg = 15500 g)

Number of atoms = ?

Solution:

Number of moles of tungsten:

Number of moles = mass/molar mass

Number of moles = 15500 g / 183.84 g/mol

Number of moles = 84.3 mol

1 mole contain 6.022 ×10²³ atoms

84.3 mol  × 6.022 ×10²³ atoms / 1mol

507.65 ×10²³ atoms

Hey there!

Molar mass NaCl = 58.44 g/mol

58.44 g ----------------- 22.4 ( at STP )

3.2 g -------------------- Volume ??

Volume = ( 3.2 x 22.4 )  / 58.44

Volume = 71.68 / 58.44

Volume = 1.226 L

Hope this helps!

Answer:

V = 0.56 L

Explanation:

Given data:

Mass of NaCl = 3.2 g

Volume of chlorine gas = ?

Pressure and temperature = standard

Solution:

Chemical equation:

2NaCl    →     2Na + Cl₂

Number of moles of NaCl:

Number of moles = mass/molar mass

Number of moles = 3.2 g/ 58.44 g/mol

Number of moles = 0.05 mol

Now we will compare the moles of NaCl with chlorine;

              NaCl       :          Cl₂

                 2          :           1

                0.05      :       1/2×0.05 = 0.025 mol

Volume of chlorine:

PV = nRT

V = nRT/P

V = 0.025 mol × 0.0821 atm.L/mol.K × 273 K / 1 atm

V = 0.56 L