Chemistry Past Questions And Answers
Bronze is preferred to copper in the making of medals because it
- A) is stronger
- B) can withstand low temperature
- C) is lighter
- D) has low tensile strength
The decreasing order of the magnitude of energy changes is
- A) phase, chemical, nuclear
- B) chemical, nuclear, phase
- C) nuclear, phase, chemical
- D) nuclear, chemical, phase
What is the change in the oxidation number of phosphorus in the the reaction represented by the following equation? 4P (s) + 5O(2)(g) → 2P2O5(g)
- A. 0 to + 2
- B. 0 to 5
- C. +4 to + 2
- D. +4 to +5
Which of the following oxides of nitrogen is unstable in air?
- A. NO2
- B. NO
- C. N2O4
- D. N2O5-
The property of concentrated H2SO4 that makes it suitable for preparing HNO3 is its
- A) boiling point
- B) density
- C) oxidizing properties
- D) dehydrating properties
Detergent is more efficient than soap in cleansing clothes and dishes because of the following reasons except that:
- A) the corresponding Ca and Mg compound formed is soluble in H2O
- B) detergents are not affected by hardness of water
- C) it cleans better than soap
- D) it is less expensive
The hybridization of the central atom in a molecule
- A) dictates the shape of the molecule
- B) shortens the sigma bond in the molecule
- C) distorts the shape of the molecule
- D) serves to explain the shape of the molecule
When coal is heated at 1000 - 1300°C the product is
- A) Coal gas
- B) Coal liquid
- C) Coal peat
- D) Coal flash
A characteristic reaction of the compounds with the general formula CnH2n is
- A. Esterification
- B. Polymerization
- C. Decarboxylation
- D. Substitution
4.0 g of sodium hydroxide in 250 cm3 of solution contains?
- A. 0.40 moles per dm3
- B. 0.10 moles per dm3
- C. 0.04 moles per dm3
- D. 0.02 moles per dm3