class 10 chemical reactions and equations

A substance which oxidises itself and reduces other is known as -

• oxidising agent

• reducing agent

• both of these

• none of these

A student added dilute HCl to a test tube containing zinc granules and made following observations:

• the zinc surface became dull and black

• a gas evolved which burnt with a pop sound

• the solution remained colourless

• the solution becomes green in colour

The reaction in which two compounds exchange their ions to form two new compounds is -

• a displacement reaction

• a decomposition reaction

• an isomerization reaction

• a double displacement reactions

When copper powder is heated it gets coated with-

• black copper oxide

• yellow copper oxide

• red copper oxide

• None of these

Combination of phosphorus and oxygen is an example of -

• oxidation

• reduction

• rancidity

• None of these

Before burning in air, the magnesium ribbon is cleaned by rubbing with a sand paper to:

• Make the ribbon surface shinier

• Remove the layer of magnesium oxide from the ribbon surface

• Remove the layer of magnesium carbonate from the ribbon surface

• Remove the moisture from the ribbon surface

In a chemical reaction between sulphuric acid and barium chloride solution the white precipitates formed are of:

• Hydrochloric acid

• Barium sulphate

• Chlorine

• Sulphur

The respiration process during which glucose undergoes slow combustion by combining with oxygen in the cells of our body to produce energy, is a kind of:

• Exothermic process

• Endothermic process

• Reversible process

• Physical process

A chemical reaction does not involve:

• Formation of new substances having entirely different properties than that of the reactants

• Breaking of old chemical bonds and formation of new chemical bonds

• Rearrangement of the atoms of reactants to form new products

• Changing of the atoms of on element into those of another element to form new products

All the methods mentioned below can be used to prevent the food from getting rancid except:

i. Storing the food in the air-tight containers

ii. Storing the food in refrigerator

iii. Keeping the food in clean and covered containers

iv. Always touching the food with clean hands

• (i) and (ii)

• (i) and (iii)

• (i), (iii) and (iv)

• (iii) and (iv)