Question

question 1
four options are provided as possible answers to the following questions. each question
has only one correct answer. write only the letter (a - d) next to the question number
(1.1 — 1.5) in the answer book, for example 1.6 d.

11.1 the number of hydrogen atoms in one mole of ammonia (nh₃) is...
a 3
b 1,204 x 10²⁴
c 1,806 x 10²⁴
d 6,02 x 10²³

(2)

11.2 which one of the following gases occupies the largest volume at stp?
a 32 g of o₂(g)
b 34 g of nh₃(g)
c 7 g of n₂(g)
d 4 g of he(g)

(2)

11.3 real gas behaviour deviates from ideal gas behaviour at...
a low temperatures and low pressures
b moderate temperatures and high pressures
c moderate temperatures and low pressures
d low temperatures and high pressures

(2)

11.4 in a chemical reaction, the difference between the potential energy of the
products and the potential energy of reactants is equal to:
a enthalpy of the reaction
b rate of the reaction
c enthalpy change of the reaction
d total potential energy of the particles

(2)

11.5 which one of the following is the correct description of a solution of hydrochloric
acid of concentration 0,1 mol·dm⁻³?
a dilute strong acid
b dilute weak acid
c concentrated strong acid
d concentrated weak acid

(2)
10

Explanation:

11.1

Step1: Moles of \(NH_3\)

1 mole of \(NH_3\) has 3 moles of H atoms (from \(NH_3\) formula: 1 N, 3 H).

Step2: Atoms of H

Using Avogadro's number (\(N_A = 6.02\times10^{23}\) atoms/mol), moles of H = 3 mol.
Number of H atoms = \(3\times6.02\times10^{23}=1.806\times10^{24}\)? Wait, no—wait, 3 moles: \(3\times6.02\times10^{23}=1.806\times10^{24}\)? Wait, option B is \(1.204\times10^{24}\), option C is \(1.806\times10^{24}\). Wait, 1 mole \(NH_3\) has 3 moles H. So \(3\times6.02\times10^{23}=1.806\times10^{24}\), which is option C? Wait, no—wait, 6.02×10²³ is Avogadro's number. 3 moles: 3×6.02×10²³ = 1.806×10²⁴. So answer is C? Wait, no, wait: 1 mole \(NH_3\) has 3 moles H. So number of H atoms: 3 × \(N_A\) = 3×6.02×10²³ = 1.806×10²⁴. So option C.

Wait, but let's check options:
A: 3 (moles? No, atoms? No, 3 moles would be 3×6e23, so A is wrong.
B: 1.204×10²⁴ is 2 moles (2×6.02×10²³=1.204×10²⁴), so no.
C: 1.806×10²⁴ is 3×6.02×10²³, correct.
D: 6.02×10²³ is 1 mole, wrong. So 11.1 answer is C? Wait, no, wait the question is "the number of hydrogen atoms in one mole of ammonia". So 1 mole \(NH_3\) has 3 moles H. So number of H atoms: 3 × \(N_A\) = 3×6.02×10²³ = 1.806×10²⁴. So option C.

11.2

Step1: Moles of each gas

At STP, volume is proportional to moles (Avogadro's law: \(V \propto n\) at constant T,P). So calculate moles (\(n = \frac{m}{M}\)):

• A: \(O_2\), \(M = 32\) g/mol. \(n = \frac{32}{32}=1\) mol.
• B: \(NH_3\), \(M = 17\) g/mol. \(n = \frac{34}{17}=2\) mol.
• C: \(N_2\), \(M = 28\) g/mol. \(n = \frac{7}{28}=0.25\) mol.
• D: \(He\), \(M = 4\) g/mol. \(n = \frac{4}{4}=1\) mol.

Step2: Compare moles

Largest moles → largest volume. \(NH_3\) has 2 mol, largest. So answer is B.

11.3

Ideal gas assumptions: negligible volume of molecules, no intermolecular forces. Real gases deviate when these assumptions fail: at low temperatures (molecules move slowly, intermolecular forces become significant) and high pressures (molecules are close, volume of molecules is not negligible). So option D: Low temperatures and high pressures.

11.4

Answer:

s:
11.1 C
11.2 B
11.3 D
11.4 C
11.5 A