Chemistry Past Questions And Answers
In the electrolysis of a concentrated solution of sodium chloride using electrodes, which of the following ions are discharged at the cathode and anode respectively?
- A. Na+ and Cl-
- B. Na+ and OH-
- C. H+ and OH-
- D. H+ and Cl-
Which of the following compounds would you expect to show positive iodoform test? (i) Butanone
(ii) Propanoic acid
(iii) Ethanol
(iv) Benzaldehyde
(v) But-2-one
- A) (i) and (ii)
- B) (i) and (iii)
- C) (iv) and (v)
- D) (ii) and (iii)
How many moles of limestone will be required to produce 5.6g of CaO?
- A) 0.20 mol
- B) 0.10 mol
- C) 1.12 mol
- D) 0.56 mol
Which of the following processes is used in food preservation in an industry?
- A. Carbon dating
- B. Ieeadiation of gamma rays
- C. Nuclear fission
- D. Nuclear fusion
Elements X and Y have electronic configurations 1s 2 2s 2 2p 4 and 1s 2 2s 2 2p 6 3s 2 3p 1 respectively. When they combine, the formula of the compound formed is
- A) XY
- B) X2Y
- C) Y2X3
- D) X2Y3
The radio isotope used in industrial radiography for the rapid checking of faults in welds and casting is?
- A) carbon-14
- B) phosphorus-32
- C) cobalt
- D) iodine-131
What condition favours the formation of the product for the endothermic reaction, \(N_2O_{4(g)} \rightarrow 2NO_{2(g)}\)?
- A) A decrease in pressure
- B) A decrease in volume
- C) An increase in pressure
- D) A constant volume
When sodium atom form the ion Na+,
- A. it gains one proton
- B. it achieves a noble gas configuration
- C. its atomic number increases
- D. it gains one electron
The following salts are readily soluble in water except
- A. Na2CO3
- B. Pb(NO3)2
- C. KCI
- D. CuCO3
Cu2+(aq) + 4NH3(g) ↔ [Cu(NH3)4]2+(aq) In the reaction above, what is the effect of precipitating Cu2+(aq) as CuS(s)?
- A. NH3(g) concentration will decrease
- B. more NH3(g)
- C. The equilibrium will shift to the right
- D. There will be no effect