40. Reaction $C_{16}H_{34} → 2 C_5H_{12} + C_{11}H_{22}$ represents:

A. Cracking ✔

Explanation:
Large alkane breaks into smaller alkanes/alkenes → cracking.

1. The number of orbitals in a p-sub level of an atom is

A. 2
B. 3 ✔

C. 5
D. 6

Explanation:
A p-subshell consists of three orbitals: $p_x$, $p_y$, and $p_z$.

2. Which of the following electron configurations represents an atom in its ground state?

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

C. $1s^2 2s^1 2p^3$
D. $1s^2 2s^2 2p^6 3s^0$

Explanation:
In the ground state, electrons occupy the lowest possible energy levels.

3. A beam of particles was passed between charged plates as shown in the diagram.

X, Y and Z are respectively

A. electron, neutron and proton
B. electron, proton and neutron ✔

C. proton, neutron and electron
D. proton, electron and neutron

Explanation:
Electrons are deflected toward the positive plate, protons toward the negative plate, while neutrons are undeflected.

4. Which of the following ions has an electron configuration different from the others?

A. $^{17}Cl^-$
B. $^{8}O^{2-}$ ✔

C. $^{12}Mg^{2+}$
D. $^{13}Al^{3+}$

Explanation:
$O^{2-}$ has 10 electrons, while the others have 18 electrons.

5. The atomic radii of metals are usually

A. greater than their ionic radii ✔

B. equal to their ionic radii
C. less than their ionic radii
D. less than those of non-metals in the same period

Explanation:
Metal atoms lose electrons to form smaller positive ions.

6. Two elements X and Y are in the same group because they have the same

A. number of electronic shells
B. number of valence electrons ✔

C. atomic size
D. atomic number

Explanation:
Elements in the same group have the same number of outer-shell electrons.

7. The d-block elements are paramagnetic because they

A. contain paired electrons repelled by a magnetic field
B. contain unpaired electrons in partially filled $3d$ orbitals ✔

C. have delocalized valence electrons
D. contain only paired electrons

8. Which statements about a radioactive substance are correct?

I. It emits radiation continuously and spontaneously.
II. The emitted radiations are affected by temperature and pressure.
III. The radiation can penetrate opaque matter.

A. II only
B. I and II only
C. I and III only ✔

D. II and III only

9. Which of the following elements is a metalloid?

A. Carbon
B. Oxygen
C. Silicon ✔

D. Sodium

10. Which of the following halogens is liquid at room temperature?

A. Chlorine
B. Fluorine
C. Iodine
D. Bromine ✔

11. The shape of a graphite crystal is

A. tetrahedral
B. pyramidal
C. hexagonal ✔

D. octahedral

12. The compound formed by the combination of two elements with a large electronegativity difference is likely to be

A. covalent
B. ionic ✔

C. metallic
D. molecular

Explanation:
Large electronegativity difference favors ionic bonding.

18. Consider the reaction:
$xCH_3OH + yO_2 \rightarrow 2CO_2 + zH_2O$

A. 2, 3 and 4 ✔

B. 2, 4 and 3
C. 1, 2 and 3
D. 1, 3 and 5

13. The complex compound formed when aluminium dissolves in aqueous sodium hydroxide is

A. $Na_2Al(OH)_4$ ✔

B. $NaAl(OH)_4$
C. $NaAl(OH)_3$
D. $Na_3Al(OH)_3$

14. Vapour pressure of a liquid depends on

I. Temperature
II. Rate of condensation
III. Cohesive forces

A. II only
B. I and II only
C. I and III only ✔

D. II and III only

15. MgO does not readily dissolve in water because

A. of its high melting point
B. it is covalent
C. it forms hydroxide in water
D. its lattice energy is greater than its hydration energy ✔

16. Mass of $CaCl_2$ formed

Percentage reacted $= 25.6\%$ of $CaCO_3$
Mass reacted $= 25.6g$
Moles of $CaCO_3 = \frac{25.6}{100} = 0.256$
Moles of $CaCl_2 = 0.256$
Mass $= 0.256 \times 111 \approx 27.8g$

A. 4.00g
B. 4.44g
C. 18.9g
D. 27.8g ✔

17. Number of sulphur atoms in $3.20g$ of $SO_2$

Molar mass of $SO_2 = 64g$
Moles $= \frac{3.20}{64} = 0.05$
Atoms $= 0.05 \times 6.02 \times 10^{23}$
$= 3.01 \times 10^{22}$

A. $3.01 \times 10^{22}$ ✔

B. $6.02 \times 10^{22}$
C. $6.02 \times 10^{23}$
D. $1.20 \times 10^{24}$

20. A gas is identified as chlorine if it turns

A. damp blue litmus red
B. limewater milky
C. lead ethanoate paper black
D. starch iodide paper blue-black ✔

21. The law explaining the formation of $MCl_2$ and $MCl$ is the law of

A. conservation of mass
B. definite proportion
C. multiple proportion ✔

D. reciprocal proportion

22. Which metal readily displaces hydrogen from steam?

A. Copper
B. Lead
C. Magnesium ✔

D. Silver

23. Volume occupied by $0.4g$ of hydrogen gas at STP

Moles $= \frac{0.4}{2} = 0.2$
Volume $= 0.2 \times 22.4 = 4.48dm^3$

A. $2.24dm^3$
B. $4.48dm^3$ ✔

C. $22.4dm^3$
D. $44.8dm^3$

24. Change from gas directly to solid is called

A. condensation
B. evaporation
C. sublimation ✔

D. precipitation

25. $H_2O$ is liquid while $H_2S$ is gas because $H_2O$ has

A. weak intermolecular forces
B. strong hydrogen bonding ✔

C. induced dipole forces
D. ionic forces

26. Constant random motion of molecules explains why liquids

A. solidify
B. maintain volume
C. are incompressible
D. have no definite shape ✔

27. Gas with the lowest rate of diffusion

A. $Cl_2$ ✔

B. $H_2$
C. He
D. $O_2$

28. Energy evolved when magnesium burns in air is

A. heat
B. heat and sound
C. light and heat ✔

D. sound

29. Substance that reacts with $NH_4NO_3$ to give ammonia is

A. HCl
B. NaOH ✔

C. $CH_3COOH$
D. $CaSO_4$

30. On heating, all decompose except

A. ammonium trioxocarbonate (IV) ✔

B. calcium trioxocarbonate (IV)
C. lead (II) trioxocarbonate (IV)
D. zinc trioxocarbonate (IV)

31. A strong base has a pH of

A. 1
B. 5
C. 9
D. 13 ✔

32. Hydrolysis of $NH_4Cl$ gives

A. an acidic solution ✔

B. alkaline solution
C. buffer solution
D. neutral solution

33. Oil paint stain is best removed using

A. brine
B. detergent
C. kerosene ✔

D. warm water

34. Correct deduction from the solubility graph is

A. solubility of U unaffected by temperature
B. solubility of S decreases with temperature
C. T is most soluble ✔

D. S is least soluble

35. Which factor does not affect the rate of reaction?

A. Particle size of CuO
B. Concentration of $H_2SO_4$
C. Temperature
D. Pressure ✔

36. The activation energy for the reaction is

A. 4 kJ
B. 60 kJ ✔

C. 80 kJ
D. 120 kJ

37. The reaction represented by the graph is

A. endothermic
B. exothermic ✔

C. catalytic
D. spontaneous

38. Devices that function on redox reactions are

I. Dry cell
II. Car battery
III. Electric generator

A. I and II only ✔

B. II and III only
C. I and III only
D. I, II and III

39. Oxidation number of Fe in $[Fe(CN)_6]^{3-}$ is

A. +3 ✔

B. +2
C. -2
D. -3

40. The process represented by
$C_{16}H_{34} \rightarrow C_5H_{12} + C_{11}H_{22}$

A. cracking ✔

B. fermentation
C. polymerization
D. reforming