Question

2. Which of the following statements is true (explain why)?
a. A sample of oxygen gas at 273K will have a higher urms than a sample of oxygen at 1000K
b. A sample of hydrogen gas at 273K will have more molecules that are able to achieve a a speed of 2000m/s than a sample of oxygen gas at 1000K (number of moles remaining constant)
c. A sample of hydrogen gas at 273K will have a higher urms than a sample of the same gas at 1000K
d. None of these statements are true
e. All of these statements are true

3. Which of the following statements regarding energy entering a system is false (explain why)?
a. Energy cannot enter or leave a system from the surroundings in the case of an isolated system
b. Both heat (q) and work (w) would require a positive sign
c. Heat (q) would require a negative sign, while work (w) would require a positive sign
d. All of these statements are true
e. All of these statements are false

4. Recall that the internal energy of a system is a state function and depends only on temperature. In the isothermal expansion of an ideal gas, which of the following statements are true (explain why)?
a. The gas absorbs energy from its surroundings
b. The gas does work
c. The change in internal energy remains constant
d. Only a and b are true
e. All of these statements are true

5. The electron configuration for Ge is [Ar] (3d^10)(4s^2)(4p^2) What is the maximum number of electrons that can have an ml value equal to 0 (show the calculations)?

a. 8

b. 15

c. 16

d. 32

Answer 1

2.The statement that the rms velocity of H at 273K is more than that of O2 at 1000K is correct.

The rms velocity of a gas = square root of 3RT/M

That is the velocity of a gas is directly proportional to Temperature and inversely proportional to molar mass.

While comparing H2 and O2 the tempertaute is increased 4 timesbut the molar mass is increased by 16 times(2 and 32 for H2 and O2 respectively).

Thus the rms velocity of H 2 at 273K is nearly twice that of O2 at 1000K.

Q30

The statement C is false.

In an isolated system no energy, no mass is allowed to leave or enter the system.

When energy is entering the system, Q is positive (heat absorbed) and work is done on the system so it would be positive.

So the statement in which Q, heat is negative is false.(Q negative means energy is given by the system)

Q4)State ment D is correct .

That is in isothermal expnsion of gas work is done by the gas , thus W = negative

From first law of thermodynamics, delta U = Q + w .

In an isothermal expansion of an ideal gas, the change in internal energy is zero. (as t = constant).

Thus Q = -W. Since W is negative Q is positive, which means heat is absorbed by the system.

Q5)Answer is 15

All S electrons have m value 0

thus 1s , 2s, 3s, 4s all with two electrons each = 8 electrons

Among the P orbital pz has m=0

Thus 2 electrons from 2p⁶, 2 from 3p⁶ and 1 from 4p²[ 4p_x¹4pz1] total = 5

From 3d¹⁰ , 2 electrons can have m value 0( d_z²) , total = 2

So from all the orbitals of Ge, the total electrons with m=0 are [8 + 5 + 2] = 15.