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1. Brass gets discoloured in air because of the presence of which of the following gases in air?
Explanation: Hydrogen sulphide

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2. Which of the following is a non metal that remains liquid at room temperature?
Explanation: Bromine

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3. Chlorophyll is a naturally occurring chelate compound in which central metal is
Explanation: magnesium

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4. The gas usually filled in the electric bulb is
Explanation: nitrogen

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5. Washing soda is the common name for
Explanation: Sodium carbonate

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6. Quartz crystals normally used in quartz clocks etc. is chemically
Explanation: silicon dioxide

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7. The hardest substance available on earth is
Explanation: Diamond

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8. The variety of coal in which the deposit contains recognisable traces of the original plant material is
Explanation: peat

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9. Tetraethyl lead is used as
Explanation: petrol additive

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10. The inert gas which is substituted for nitrogen in the air used by deep sea divers for breathing, is
Explanation: Helium

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