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A-Level CAIE Physics 15 1 The Mole Question Bank

Practice A-Level CAIE Physics 15 1 The Mole questions by syllabus topic with past-paper context, marks, difficulty and question previews on Eduninja.

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Question 1

1

An ideal gas has volume V and pressure p. For this gas, the product p V is given by the expression where m is the mass of a molecule of the gas.

structured5 marks

Question 1(b)

1(b)

A gas cylinder of volume \(2.1 \times 10^{4} \mathrm{~cm}^{3}\) contains helium-4 gas at pressure \(6.1 \times 10^{5} \mathrm{~Pa}\) and temperature \(12^{\circ} \mathrm{C}\). Helium-4 may be assumed to be an ideal gas.

structured5 marks

Question 1(b)(i)

1(b)(i)

Determine, for the helium gas, 1. the amount, in mol, amount = mol [3] 2. the number of atoms. number =

Easystructured5 marks

Answer

1. \(p V=n R T \quad \mathrm{C} 1\) \(n=\left(6.1 \times 10^{5} \times 2.1 \times 10^{4} \times 10^{-6}\right) /(8.31 \times 285) \quad\) C1 \(n=5.4 \mathrm{~mol} \quad\) A1 2. either \(N=n N_{\mathrm{A}}\) \(\begin{array}{ll}=5.4 \times 6.02 \times 10^{23} & \text { C1 } \\ =3.26 \times 10^{24} & \text { A1 }\end{array}\) or p V=N k T \(N=\left(6.1 \times 10^{5} \times 2.1 \times 10^{4} \times 10^{-6}\right) /\left(1.38 \times 10^{-23} \times 285\right)\) \(N=3.26 \times 10^{24}\)

Question 2

2

the rate h of thermal energy gained by the ice from the surroundings. W

structured2 marks

Question 2(b)

2(b)

The variation with volume V of the pressure p of an ideal gas as it undergoes a cycle ABCA of changes is shown in Fig. 2.1. The temperature of the gas at A is 290 K . The temperature at B is 870 K . Determine

structured2 marks

Question 2(b)(i)

2(b)(i)

the amount, in mol, of gas, amount = mol

Mediumstructured2 marks

Answer

p V=n R T either at A, \(1.2 \times 10^{5} \times 4.0 \times 10^{-3}=n \times 8.31 \times 290\) or at B, \(\quad 3.6 \times 10^{5} \times 4.0 \times 10^{-3}=n \times 8.31 \times 870\) C1 \(n=0.20 \mathrm{~mol}\) A1

Question 2

2

+w.

structured1 marks

Question 2(a)

2(a)

Explain what is meant by the Avogadro constant.

Easystructured2 marks

Answer

the number of atoms in 12 g of carbon-12

Question 2(b)

2(b)

Argon-40 \(\left({ }_{18}^{40} \mathrm{Ar}\right)\) may be assumed to be an ideal gas. A mass of 3.2 g of argon- 40 has a volume of \(210 \mathrm{~cm}^{3}\) at a temperature of \(37^{\circ} \mathrm{C}\). Determine, for this mass of argon-40 gas,

structured1 marks

Question 2(b)(i)

2(b)(i)

the amount, in mol, amount = mol

Mediumstructured1 marks

Answer

amount =3.2 / 40

Question 2

2

2 marks

Question 2(a)

2(a)

State what is meant by a mole.

Easystructured2 marks

Answer

amount of substance containing same number of particles as in 0.012 kg of carbon-12

Question 2

2

electric potential energy. energy = J

structured3 marks

Question 2(c)

2(c)

Helium-4 may be assumed to behave as an ideal gas. A cylinder has a constant volume of \(7.8 \times 10^{3} \mathrm{~cm}^{3}\) and contains helium-4 gas at a pressure of \(2.1 \times 10^{7} \mathrm{~Pa}\) and at a temperature of 290 K . Calculate, for the helium gas,

structured2 marks

Question 2(c)(i)

2(c)(i)

the amount of gas, amount = mol

Mediumstructured2 marks

Answer

p V=n R T \(2.1 \times 10^{7} \times 7.8 \times 10^{-3}=n \times 8.3 \times 290 \quad\) C1 \(n=68 \mathrm{~mol}\) A1 [2]

Question 2

2

1 marks

Question 2(b)

2(b)

A sealed vessel contains a mass of 0.0424 kg of an ideal gas at \(227^{\circ} \mathrm{C}\). The pressure of the gas is \(1.37 \times 10^{5} \mathrm{~Pa}\) and the volume of the gas is \(0.640 \mathrm{~m}^{3}\). Calculate:

structured1 marks

Question 2(b)(ii)

2(b)(ii)

the mass of one molecule of the gas

Mediumstructured1 marks

Answer

mass \(=0.0424 /\left(1.27 \times 10^{25}\right)\) \[ =3.34 \times 10^{-27} \mathrm{~kg} \] A1

Question 2

2

1 marks

Question 2(a)

2(a)

State what is meant by the Avogadro constant \(N_{\mathrm{A}}\).

Easystructured1 marks

Answer

number of atoms of carbon-12 in 0.012 kg of carbon-12

Question 3

3

4 marks

Question 3(a)

3(a)

State what is meant by an ideal gas.

Easystructured1 marks

Answer

obeys the equation p V / T= constant (accept p V=n R T )

Question 3(b)

3(b)

A storage cylinder for an ideal gas has a volume of \(3.0 \times 10^{-4} \mathrm{~m}^{3}\). The gas is at a temperature of \(23^{\circ} \mathrm{C}\) and a pressure of \(5.0 \times 10^{7} \mathrm{~Pa}\).

structured3 marks

Question 3(b)(ii)

3(b)(ii)

The gas leaks slowly from the cylinder so that, after a time of 35 days, the pressure has reduced by 0.40 %. The temperature remains constant. Calculate the average rate, in atoms per second, at which gas atoms escape from the cylinder.

Hardstructured3 marks

Answer

pressure \(\propto\) amount of substance

Question 3

3

1 marks

Question 3(a)

3(a)

State what is meant by an ideal gas.

Easystructured1 marks

Answer

obeys the equation p V / T= constant (accept p V=n R T )

Question 3(b)

3(b)

A storage cylinder for an ideal gas has a volume of \(3.0 \times 10^{-4} \mathrm{~m}^{3}\). The gas is at a temperature of \(23^{\circ} \mathrm{C}\) and a pressure of \(5.0 \times 10^{7} \mathrm{~Pa}\).

structured0 marks

Question 3(b)(ii)

3(b)(ii)

The gas leaks slowly from the cylinder so that, after a time of 35 days, the pressure has reduced by 0.40 %. The temperature remains constant. Calculate the average rate, in atoms per second, at which gas atoms escape from the cylinder.

Hardstructured0 marks

Answer

pressure \(\propto\) amount of substance

Question 3

3

0 marks

Question 3(b)

3(b)

A sample of \(0.26 \mathrm{~m}^{3}\) of an ideal gas is at pressure \(2.0 \times 10^{5} \mathrm{~Pa}\) and temperature 290 K . Determine:

structured0 marks

Question 3(b)(i)

3(b)(i)

the number N of molecules of the gas

Easystructured0 marks

Answer

p V=N k T C1 \[ \begin{aligned} N =\left(2.0 \times 10^{5} \times 0.26\right) /\left(1.38 \times 10^{-23} \times 290\right) =1.3 \times 10^{25} \end{aligned} \] A1