1. Brass gets discoloured in air because of the presence of which of the following gases in air? A. Oxygen B. Hydrogen sulphide C. Carbon dioxide D. Nitrogen Answer: Option B 2. Which of the following is a non metal that remains liquid at room temperature? A. Phosphorous B. Bromine C. Chlorine D. Helium Answer: Option B 3. Chlorophyll is a naturally occurring chelate compound in which central metal is A. copper B. magnesium C. iron D. calcium Answer: Option B 4. Which of the following is used in pencils? A. Graphite B. Silicon C. Charcoal D. Phosphorous Answer: Option A 5. Which of the following metals forms an amalgam with other metals? A. Tin B. Mercury C. Lead D. Zinc Answer: Option B 6. Chemical formula for water is A. NaA1O 2 B. H 2 O C. Al 2 O 3 D. CaSiO 3 7. The gas usually filled in the electric bulb is A. nitrogen B. hydrogen C. carbon dioxide D. oxygen An
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