Chemistry Past Questions And Answers
The noble gas, argon, is used for
- A) electrical arc welding
- B) welding brass
- C) underwater welding
- D) steel-welding
Which of the following is a physical change?
- A) Exposing white phosphorus to air
- B) Burning kerosene
- C) Dissolving calcium in water
- D) Freezing ice cream
The gas that is most useful in protecting humans against solar radiation is
- A) chlorine
- B) ozone
- C) carbon (IV) oxide
- D) hydrogen sulphide
When ethanol is heated with excess concentrated tetraoxosulphate (VI) acid, the organic product formed is
- A. ethanal
- B. ethanoic acid
- C. ethane
- D. ethene
Which of the following phenomenna lead to decrease in volume of a liquid in an open container?
- A. Brownian motion
- B. Diffusion
- C. Evaporation
- D. Sublimation
The most common process in the extraction of metals from their ore is
- A. catalysis
- B. electrolysis
- C. oxidation
- D. reduction
Which of the following gives a precipitate when treated with NaOH solution?
- A. AlCl3
- B. NH4CL
- C. CH3COONa
- D. Na2CO3
A common characteristic shared by iron and aluminium is that both?
- A. are extracted by reduction methods
- B. form only basic oxides
- C. show oxidation states of +2 and +3
- D. form soluble hydroxides
Esterification of propane 1,2,3-triol and unsaturated higher carboxylic acids will produce
- A. fats
- B. soap
- C. methly-propanoate
- D. alkanols
In the course of purifying water for town supply the water is passed through large settlings tanks, containing sodium aluminate (III) to remove
- A) large particles
- B) germs
- C) fine particles
- D) odour