does anyone have the 2020 paper for chemistry

Answer:

The mass of an atom is equal to the protons plus the neutrons

Answer:

loss of mass

Explanation:

your welcome :)

Answer:

a.cocentration es la respuesta

I am going to put them in order

R r

R RR rR

r rR rr

Answer:

202.5 K

Explanation:

Answer:

B. 0.7%

Explanation:

Given data:

Actual boiling point = 82.5°C

Experimental boiling point = 83.1°C

Percent error = ?

Solution:

Formula:

Percent error = ( actual value - experimental value / actual value )×100

by putting values,

Percent error = (82.5°C - 83.1 °C /82.5°C) × 100

Percent error = 0.007 × 100

Percent error = 0.7 %

Negative sign shows that experimental value is greater than accepted value. It can not written in result.

Answer:

Explanation:

Rutherford gold experiment gave the explanation to some observations made on atoms.

When he shot the gold foil, most of the [tex]\alpha[/tex]-particles passes through the foil undeflected nor absorbed. This faction of the particles propagated the foil as if there was nothing placed on their path.

The surprising behavior of a few of the [tex]\alpha[/tex]-particles was that they were deflected from their initial path on hitting the gold foil.

This implies that there is a part of the gold foil which has the same charge as the [tex]\alpha[/tex]-particles, and more massive than the particles. Thus, he was able to determine the nucleus of an atom.

Answer:

Joules first law is a law that expresses the relatioship between heat that is generated and the current flowing heat thats through a conductor. The second law says that internal energy is independent of volume and pressure, depending only on temperature!

Explanation:

Answer:hope it helps

Explanation:

Answer:

Specific gravity compares the density of a substance to the density of air.

Specific gravity is compared the density of a substance to the density of water.

Specific Gravity is a dimensionless quantity that can be defined as the ratio of the density of a substance to the density of the water at a particular temperature.

The mathematical formula of the specific gravity can be written as:

Specific gravity = density of substance / density of water

The density of water at 4°C is used as a reference point as water has the highest density of 1000 kg/m³.  Specific gravity or relative gravity does not have any dimension as it is a dimensionless quantity.

Specific gravity is the ratio of a substance’s density to that of water at a specific temperature. The temperature plays an important role in determining the specific gravity of a substance.

Therefore, specific gravity is a characteristic of the substance at a particular temperature and pressure that also affects the specific gravity.

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Answer:

The possible valances can be determined by electron configuration and electron negativity

Good Luck even though this was asked 2 weeks ago

Explanation:

All atoms strive for stability. The optima electron configuration is the electron configuration of the VIII A family or inert gases.

Look at the electron configuration of the nonmetal and how many more electrons the nonmetal needs to achieve the stable electron configuration of the inert gases. Non metals tend to be negative in nature and gain electrons. ( They are oxidizing agents)

For example Florine atomic number 9 needs one more electron to reach a valance number of 8 electrons to equal Neon atomic number 10. Hence Flowrine has a valance of -1

Oxygen atomic number 8 needs two more electrons to reach a valance number of 8 electrons to equal Neon atomic number 10. Hence Oxygen has a valance charge of -2.

Non metals with a low electron negativity will lose electrons when reacting with another non metal that has a higher electron negativity. When the non metal forms an ion it is necessary to look at the electron structure to determine how many electrons the element can lose to gain stability.

For example Chlorine which is normally -1 like Florine when it combines with oxygen can be +1, +3, + 5 or +7. It can lose its one unpaired electron, or combinations of the unpaired electron and sets of the three pairs of electrons.

Explanation:

The two ways that energy can be transferred are by doing work and by heat transfer.

Answer:

I give u three in explanation

Explanation:

Crushing the can, stomping on the can, and squishing the can

Explanation:

the model assumes that the electron is a wave and tries to describe the regions in space orb orbitals where most likely to be found

Answer:

Sodium oxide reacts exothermically with cold water to produce sodium hydroxide solution. A concentrated solution of sodium oxide in water will have pH 14. ... For example, it reacts with dilute hydrochloric acid to produce sodium chloride solution.

Answer:

920mL of water

Explanation:

To solve this question we need to find as first the mass that must be added of water to make 1000mL of syrup using specific gravity. Thus, we can know the volume of water that mus be added:

1.31 is 1.31g/mL. In 1000mL = 1310g/1000mL. As the mass added of sucrose is 850g, the mass of water = Volume of water is:

1310g - 850g = 460g of water = 460mL to make 1L, To make 2L the amount of water that must be added is:

460mL * 2  =

The number of milliliters of water are used to prepare two liters of syrup is 920 mL of water.

Given that,

Based on the above information, the calculation is as follows:

1.31 is = 1.31g/mL.

Now

In 1000mL = [tex]1310g \div 1000mL[/tex].

Now if the mass is added so the mass of water should be equivalent to the volume of the water.

= 1310g - 850g

= 460g of water

Now

= 460mL for 1L,

To make 2L the water should be  

= 460mL (2)

= 920mL of water

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Answer:

Mg2+

Explanation:

The most reactive ions from the given choices is the magnesium ion. This is because it is higher in the activity series of metals.

Zinc ion is below this specie in the activity series.

As a rule, ions above another on the activity series are generally more reactive than those below.

From any solution, magnesium ion will displace the zinc ion in such process.

The position of metallic ions determines their reactivity.

Answer:

M₂ = 0.34 M

Explanation:

Given data:

Molarity of NaOH =M₁ =  0.200 M

Volume of HF =V₂=  18.25 mL

Volume of NaOH added = V₁ = 31.20 mL

Molarity of HF solution = M₂ = ?

Solution:

M₁V₁  =  M₂V₂

by putting values,

0.200 M × 31.20 mL = M₂ × 18.25 mL

M₂ = 0.200 M × 31.20 mL /  18.25 mL

M₂ = 6.24 M.mL / 18.25 mL

M₂ = 0.34 M

Answer: V₂ = 37.71mL

Explanation: To determine the new volume of Helium gas, use the Combined Gas Law, which states the following relationship among pressure, volume and temperature:

[tex]\frac{P_{1}V_{1}}{T_{1}} =\frac{P_{2}V_{2}}{T_{2}}[/tex]

where index 1 relates to the initial state of the gas and index 2 to the final state of the gas.

Temperature is in Kelvin, so:

T = °C + 273

For this situation, standard pressure is 1 atm. Temperatures will be:

T₁ = 20 + 273 = 293 K

T₂ = 91 + 273 = 364 K

Solving:

[tex]V_{2}=\frac{T_{2}P_{1}V_{1}}{P_{2}T_{1}}[/tex]

[tex]V_{2}=\frac{364*1*85}{2.8*293}[/tex]

[tex]V_{2}=\frac{30940}{820.4}[/tex]

[tex]V_{2}=[/tex] 37.71

The new volume of He gas is 37.71 mL.

Given :

A gas with a volume of 2 L at 25°C is placed into a container that is 4 L.

To Find :

The new temperature of the gas.

Solution :

Since, their is no information regarding pressure. We will assume that pressure is constant.

Now, we know when at constant pressure, volume is directly proportional to volume.

[tex]\dfrac{V_1}{V_2}=\dfrac{T_1}{T_2}\\\\\dfrac{2}{4} = \dfrac{25 + 273 }{x}\\\\x = 2 \times ( 25 + 273 )\\\\x = 596\ K[/tex]

Therefore, the new temperature of the gas is 596 - 273 K = 323  K.

Answer:

Formal charge = valance electron - nonbonding electron - (1/2)bonded electron

For nitrogen atom,

Formal charge = 5 - 2 - (1/2)×6

= 5-2-3

= 0

So, the formal charge on nitrogen atom in HCN is "0".​​​

Explanation:

The formal charge on the N atom of hydrogen cyanide, HCN molecule is 0. Option B is correct.

Formal charge is defined as the individual charge of an atom. It is represented as:

Formal charge = valance electron - nonbonding electron - (1/2)bonded electron

The valence electrons in nitrogen atom is 5, there are 2 non bonding electrons and 6 bonded electrons on N atom in HCN,

Thus, For Hydrogen cyanide molecule, the formal charge on nitrogen atom is calculated as:

Formal charge

= 5 - 2 - (1/2)×6

= 5-2-3

= 0

So, the formal charge on nitrogen atom in HCN is "0".​​​

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The concentration of this acid in moles per litre : 17.41

Given

99.5% acetic acid

density=ρ=1.05 g/ml

Required

the concentration (mol/L)

Solution

99.5% dan density 1.05 g/ml (MW acetic acid = 60 g/mol)

[tex]\tt 99.5\%\times 1.05\dfrac{g}{ml}\times \dfrac{1000~ml}{L}=1044.75~g/L\\\\\dfrac{1044.75~g/L}{60~g/mol}=17.41~mol/L[/tex]

Answer:

The correct answer is D

Explanation:

In an endothermic process, energy travels from the surroundings into the system. The decrease in the temperature on the outside of the bag indicates that energy has moved from the surroundings into the system.

The other answers are incorrect. A bag cannot release “cold” into the surroundings since cold refers to the absence of heat. The surroundings become colder when heat is removed. Option B is incorrect because the cooling is due to the cold pack absorbing heat energy from its surroundings. Option C is incorrect because a cold pack absorbs heat energy from the surroundings, not vice versa.

The surroundings are losing energy and the thermometer is measuring the temperature of the surroundings as the cold pack shows an endothermic process. Therefore, Option (D) is correct.

Endothermic reactions are those in which the reactants absorb heat energy from their surroundings to form products. Endothermic reactions reduce the temperature of their surroundings and create a cooling effect. Physical processes can be endothermic in nature as well, for example, ice cubes absorb heat from their surroundings to form liquid water.

Endothermic reactions include the making of chemical bonds through the absorption of energy from the surroundings. On the other hand, exothermic reactions are in which the liberation of heat energy is generated from bond breakage.

The temperature of the cold pack is lower than the temperature of the surroundings. So the heat energy will be traveled from the surroundings to the cold pack.

Therefore, the temperature of the surroundings will fall as heat transfers to the cold pack.

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Answer:

:)

Explanation:

They are all properties of Matter. weight and formula wouldn't make sense.

Explanation:

done

..................

Answer:

c

Explanation:

solid to gas directly

Answer:

the answer would be B

Explanation:

The move vigorously it is the higher the reactivity so if you put it in order the answer would be B