Why does a blackboard appears black in colour?

• It reflects black colour

• It absorbs black colour

• It reflects all colours

• It absorbs all the colours

Which among the following metal is used for galvanization?

• Zinc

• Copper

• Iron

• Silver

What is dry ice?

• Solid Carbon dioxide

• Solid Nitrogen dioxide

• Solid Sulphur dioxide

• Solid Water

.............. gases absorb long wave (infrared) radiation from the earth and emit it again towards the earth.

• Methane

• Greenhouse

• Carbon dioxide

• Ozone

Which acid is released when an Ant bites?

• Hydrochloric Acid

• Formic Acid

• Acetic Acid

• Phosphoric Acid

Which among the following is an example of solid sol?

• Milk of Magnesia

• Foam

• Coloured gemstones

• Rubber

Which metal is responsible for Itai-Itai disease?

• Cadmium

• Nickel

• Chromium

• Mercury

198.

Which of the following metal (shown by its symbol) is generally used for making filaments of bulb?

• Fe

• An

• Ag

• W

A radio-active substance has a half-life of six months. Three-fourth of the substance will decay in.................

• six months

• ten months

• twelve months

• twenty four months

pH of the human blood is..............

• Slightly Acidic

• Highly Acidic

• Slightly Basic

• Highly Basic