1. How many isotopes does hydrogen have?

A. 2
B. 3 ✔

C. 4
D. 5

Explanation:
Hydrogen has three isotopes: protium, deuterium, and tritium.

2. Which of the following electron configurations correctly represents an inert element?

A. $1s^2 2s^2 2p^4$
B. $1s^2 2s^2 2p^6 3s^2$
C. $1s^2 2s^2 2p^6 3s^2 3p^4$
D. $1s^2 2s^2 2p^6$ ✔

Explanation:
Inert (noble) gases have completely filled outer shells.

3. What type of reaction is represented by the equation?
${^2_1D} + {^3_1H} \rightarrow {^4_2He} + {^1_0n} + \text{energy}$

A. Nuclear fission
B. Nuclear fusion ✔

C. Radioactive decay
D. Spontaneous decay

Explanation:
Light nuclei combine to form a heavier nucleus with release of energy.

4. Which of the following ions has the electron configuration $2, 8, 8$?

A. $Na^+$
B. $Mg^{2+}$
C. $F^-$
D. $Cl^-$ ✔

Explanation:
$Cl^-$ has 18 electrons, giving the configuration $2,8,8$.

5. An element with electron configuration $1s^2 2s^2 2p^6$ would have a combining power of

A. 0 ✔

B. 2
C. 6

Explanation:
This is a noble gas configuration, hence valency is zero.

6. Rare gases are stable because they

A. contain equal numbers of protons and neutrons
B. contain more electrons than protons
C. are chemically active
D. have octet structure ✔

Explanation:
A complete outer shell makes them chemically stable.

7. Which element would produce coloured ions in aqueous solution?

A. Calcium
B. Iron ✔

C. Magnesium
D. Sodium

Explanation:
Transition metals like iron form coloured ions.

8. The energy change that accompanies the addition of an electron to an isolated gaseous atom is called

A. Bond energy
B. Electronegativity
C. Electron affinity ✔

D. Ionization energy

Explanation:
Electron affinity measures the tendency to accept electrons.

9. Which of the following hydrohalic acids is the weakest?

A. HBr
B. HCl
C. HF ✔

D. HI

Explanation:
HF has the strongest H–F bond and ionizes least.

10. Which arrangement is in order of increasing metallic property?

A. $Li < Na < K$ ✔

B. $Na < Li < K$
C. $K < Na < Li$
D. $K < Li < Na$

Explanation:
Metallic character increases down Group 1.

11. Chlorine, bromine and iodine belong to the same group and

A. are gaseous at room temperature
B. form white precipitates with $AgNO_{3(aq)}$ ✔

C. react violently with hydrogen without heating
D. react with alkali only

Explanation:
Halide ions form precipitates with silver nitrate.

12. Which element can be placed in two groups in the periodic table?

A. Carbon
B. Copper
C. Hydrogen ✔

D. Oxygen

Explanation:
Hydrogen shows properties of both alkali metals and halogens.

13. The bond formed when shared electrons are donated by only one atom is

A. Covalent
B. Dative ✔

C. Ionic
D. Metallic

Explanation:
A dative bond involves donation of both electrons by one atom.

14. When element $20A$ combines with element $8Y$

A. a covalent compound AY is formed
B. an ionic compound AY is formed
C. an ionic compound AY is formed
D. an ionic compound $AY_2$ is formed ✔

Explanation:
Element 20 is Ca, element 8 is O, forming $CaO$ ($AY_2$).

15. In metallic solids, attraction exists between mobile electrons and

A. atoms
B. neutrons
C. negative ions
D. positively charged nuclei ✔

Explanation:
Metallic bonding is due to attraction between ions and delocalized electrons.

16. Which statement about displacement reactions is correct?

A. A more electropositive element displaces a less electropositive one ✔

B. A less electropositive element displaces a more electropositive one
C. Position in the series has no effect
D. It only occurs at equilibrium

Explanation:
Reactivity depends on electropositivity.

17. Volume occupied by $17g$ of $H_2S$ at STP

Molar mass of $H_2S = 2(1) + 32 = 34g$
Moles $= \frac{17}{34} = 0.5$
Volume $= 0.5 \times 22.4 = 11.2dm^3$

A. $11.2dm^3$ ✔

B. $17.0dm^3$
C. $34.0dm^3$
D. $44.8dm^3$

18. Correct coefficients for the reaction are

A. $2, 5, 2$ ✔

B. $2, 2, 5$
C. $5, 1, 2$
D. $1, 3, 2$

Explanation:
Balanced redox reaction coefficients are $x=2, y=5, z=2$.

19. Amount of magnesium containing $1.20 \times 10^{24}$ particles

Moles $= \frac{1.20 \times 10^{24}}{6.02 \times 10^{23}} \approx 2.0$

A. 0.5 moles
B. 2.0 moles ✔

C. 12.0 moles
D. 24.0 moles

20. The number of atoms in one mole is equal to the

A. Mass number
B. Oxidation number
C. Atomic number
D. Avogadro number ✔

Explanation:
One mole contains $6.02 \times 10^{23}$ particles.

21. A molar solution

A. is supersaturated
B. cannot dissolve more solute
C. contains any amount of solute
D. contains one mole of solute in $1dm^3$ ✔

Explanation:
Molarity is defined as moles per cubic decimetre.

22. A gas collected by upward delivery is

A. heavier than air
B. insoluble in water
C. lighter than air ✔

D. soluble in water

23. Excess $CO_2$ bubbled into calcium hydroxide produces

A. $CaCO_3$
B. CaO
C. $Ca(HCO_3)_2$ ✔

D. $H_2CO_3$

24. The equation $PV = constant$ illustrates

A. Boyle’s law ✔

B. Charles’ law
C. Dalton’s law
D. Gay-Lussac’s law

25. Final temperature of the gas

$\frac{V_1}{T_1} = \frac{V_2}{T_2}$
$T_2 = \frac{250 \times 300}{220} \approx 341K$

A. 183 K
B. 264 K
C. 300 K
D. 341 K ✔

26. Which equimolar solution has the highest conductivity?

A. $CH_3COOH(aq)$
B. $H_2CO_3(aq)$
C. $H_2SO_4(aq)$ ✔

D. $NaOH(aq)$

Explanation:
Strong acids produce more ions.

27. Colour of phenolphthalein in alkaline solution is

A. Colourless
B. Orange
C. Pink ✔

D. Yellow

28. Enthalpy of neutralization

A. is constant for a strong acid and strong base ✔

B. cannot be determined using calorimeter
C. is positive
D. is higher for strong acid and weak base

30. Dissolving $NH_4Cl$ makes the container cold because

A. the process is endothermic ✔

B. the process is exothermic
C. it is highly soluble
D. it forms a saturated solution

31. Which metallic oxide is amphoteric?

A. $Al_2O_3$ ✔

B. $Fe_2O_3$
C. MgO
D. $Na_2O$

32. Solubility of the salt

Moles $= \frac{50.5}{101} = 0.5$
Volume $= 0.25dm^3$
Solubility $= \frac{0.5}{0.25} = 2.0mol\,dm^{-3}$

A. $1.0mol\,dm^{-3}$
B. $2.0mol\,dm^{-3}$ ✔

C. $4.0mol\,dm^{-3}$
D. $5.0mol\,dm^{-3}$

33. Effect of increasing temperature

A. backward reaction favoured
B. forward reaction favoured ✔

C. reaction stops
D. equilibrium is reached

34. Condition that increases reaction rate

A. Increase temperature, decrease surface area
B. Increase temperature and concentration ✔

C. Decrease temperature, increase concentration
D. Decrease temperature, increase surface area

35. Value of $n$ in the equation

$Cr_2O_7^{2-} + 14H^+ + 6e^- \rightarrow 2Cr^{3+} + 7H_2O$

A. 2
B. 3
C. 6 ✔

D. 7

36. Mass of copper deposited

Charge $= 10 \times 3600 = 36000C$
Mass $= \frac{36000 \times 63.5}{96500 \times 2} \approx 11.8g$

A. 5.9 g
B. 11.8 g ✔

C. 23.7 g
D. 47.3 g

37. Metal used as sacrificial anode

A. Copper
B. Lead
C. Magnesium ✔

D. Silver

38. Electrode potential is positive when

A. electrons flow from M to hydrogen electrode ✔

B. electrons flow from hydrogen to M
C. current is high
D. equilibrium exists

39. Compound used to determine octane rating

A. 1,2,3-trimethylpentane
B. 2,3,5-trimethyloctane
C. 2,3,5-trimethylpentane
D. 2,2,4-trimethylpentane ✔

40. Compound that reacts with ethanoic acid to give a sweet-smelling liquid

A. Alkane
B. Alkanol ✔

C. Alkanal
D. Alkyne

Explanation:
Esters formed from alcohols and acids have pleasant smells.