Brown stains in vessels and clothes indicate the presence of high quantities of .......... in water.

• magnesium

• calcium

• manganese

• manganese

Chemical properties of isotopes

• must be same

• must be different

• need not be same

• need not be same

Diamond does not conduct electricity, because

• It's structure is very compact

• It is of crystalline nature

• There are only carbon atoms present in

• There are only carbon atoms present in

What are Aldehydes?

• Mild oxidising agents

• Strong oxidising agents

• Strong reducing agents

• Strong reducing agents

Synthetic detergents are prepared from

• potassium salts of higher fatty-acids

• sodium salts of higher fatty-acids

• hydrocarbons of petroleum

• hydrocarbons of petroleum

Iron and Manganese present as pollutants in water cannot be removed by

• oxidation followed by settling and filtration

• chlorination

• ion exchanges process

• ion exchanges process

The antiparticle of an electron is

• Positron

• Proton

• Alpha particles

• Alpha particles

The manufacturing of iron from iron-ore involves the process of

• Oxidation

• Reduction

• Electrolysis

• Electrolysis

The compound used in prickly-heat powder to prevent excessive sweating is

• Boric acid

• Phosphoric acid

• Carbonic acid

• Carbonic acid

50.

At low temperature, Lead behaves as a

• Semi conductor

• Super conductor

• Insulator

• Insulator