Chemistry Past Questions And Answers
The following statements are correct except
- A. energy is released when liquids change to solids.
- B. carbon atoms in gaseous methane are further apart than those in solid diamond.
- C. there is large decrease in the volume of a solid metal when pressure is applied to it.
- D. particles move faster in the gaseous state than in the liquid state.
(a) State the following laws of chemical combination: (i) Law of constant composition (ii) Law of multiple' proportion.
(b) Copper reacts with oxygen to form two oxides X and Y. On analysis, 1.535 g of X yielded 1.365 g copper and 1.450 g of Y yielded 1.160 g of cooper.
i) Determine the chemical formula of X and Y.
(ii) Calculate the mass of copper which can react with 0.500 g of oxygen to yield I. X II. Y.
(iii) Which of the laws of chemical combination is illustrated by the result in (b)(i) above. [ = 16, Cu = 63.51]
(c) Write the structure of the product responsible for the observation in each of the following reactions:
(i) A mixture of butanoic acid and ethanol warmed in the presence of concentrated H\(_2\)SO\(_4\) gives off a fragrant odour.
(ii) Sodium dissolves in propan-2-ol with effervescence to give a solution which on evaporation to dryness leaves a white precipitate.
(d) Consider the compound CH\(_3\)CH\(_2\)COOCH\(_2\)CH\(_3\).
(i) Name the compound (ii) Write the structural formula of the compound (iii) State the reagents and conditions for the formation of the compound.
Sodium chloride cannot conduct electricity in the solid state because it
- A. is a normal salt
- B. is highly soluble in water
- C. is an electrovalent compound
- D. does not contain mobile ions
Amphoteric oxides are oxides which
- A. react with water to form acids
- B. react with water to form alkali
- C. show neither acid nor basic properties
- D. react with acids alkalis
If 100 cm3 of oxygen pass through a porous plug in 50 seconds, the time taken for the same volume of hydrogen to pass through the same porous plug is? (O = 16, H = 1)
- A. 10.0 s
- B. 12.5 s
- C. 17.7 s
- D. 32.0 s
I. H = 1s1 II. N = 1s2 2s2 p3 III. O = 1s2 2s2 p4 IV. Zn = 1s2 2s2 2p6 3s2 3p6 4s2 3d10 From the above, which of the following pairs is like to be paramagnetic?
- A. I and II
- B. I and III
- C. I and IV
- D. III and IV
The ability of ionic solids is generally due to the?
- A. negative electron affinity of most atoms
- B. crystal lattice forces
- C. electron pair sharing
- D. positive ionization potentials
Detergents are manufactured with straight hydrocarbon chains so as to make them
- A. soluble
- B. biodegradable
- C. cheaper
- D. foamy
What volume of oxygen will remain after reacting 8cm3 of hydrogen with 20cm3 of oxygen?
- A. 10 cm3
- B. 12 cm3
- C. 14 cm3
- D. 16 cm3
The following substances are non-electrolytes except
- A) chloroform
- B) sugar cane
- C) acetic acid
- D) acetic acid and NaCl