Rainbows are produced by when sunlight 

• incident on rain drops hanging in the atmosphere is dispersed after suffering refraction

• incident on rain drops hanging in the atmosphere is dispersed after suffering reflection

• incident on rain drops hanging in the atmosphere is dispersed after suffering refraction and internal reflection

• incident on rain drops hanging in the atmosphere is dispersed after suffering refraction and internal reflection

The green colour seen in firework displays is due to the chloride salt of

• strontium

• barium

• sodium

• sodium

Kautilya's 'Artharshastra' mainly deals with

• economic doctrines

• social aspects

• political state craft

• political state craft

Which of the following is used in pencils?

• Graphite

• Sulphur

• Phosphorus

• Phosphorus

The branch of medicine involving synthetic chemical compounds is

• ayurveda

• allopathy

• homoeopathy

• homoeopathy

Bubbles of air rise up through liquids due to

• Surface tension and adherence

• Viscosity and buoyancy

• Air current over the liquid and buoyancy

• Air current over the liquid and buoyancy

The boiling point of liquids vary as

• pressure varies

• temperature varies

• volume varies

• volume varies

The largest source of pollution in the world is

• Herbicides and insecticides

• Automobile exhausts

• Sewage and garbage

• Sewage and garbage

Acid rain is caused due to pollution of atmosphere by

• oxides of nitrogen and sulphur

• oxides of nitrogen and phosphorus

• oxides of carbon and nitrogen

• oxides of carbon and nitrogen

The most serious air pollutant causing health hazard is

• Sulphur dioxide

• Carbon monoxide

• Ozone

• Ozone