Class X_16 May_Chemical Reactions and Equations

Fill in the blanks:

Magnesium ribbon burns with a dazzling white flame and changes into a ---------------- powder. This powder is magnesium oxide.

• white

• red

• blue

• green

When metals react with acids hydrogen gas is released. However, with nitric acid metals react to form water instead of hydrogen. This is because

• nitric acid is strong

• nitric acid is reducing in nature

• nitric acid is oxidising in nature

• nitric acid is weak

Fe₃O₄ occurs in nature as the mineral "-----------------"

• Haematite

• Iron pyrite

• Wustite

• Magnetite

100 ml of hydrogen gas reacts with 50 ml of oxygen gas. The volume of water vapour formed is ------------

• 100 ml

• 150 ml

• 125 ml

• 200 ml

1 atm =

• 1 Pa

• 10⁵ Pa

• 760 Pa

• 1.01325 x 10⁵ Pa

Which of the following metals shall not react with cold water?

• Potasium

• Lead

• Sodium

• Calcium

Slaked lime is formed by mixing quick lime in water. The reaction is

• Exothermic

• Endothermic

• Energy is neither released nor absorbed

• None

When excess of carbon dioxide gas is passed through lime water, the milkiness disappears due to the formation of

• soluble Calcium Carbonate

• soluble Calcium bicarbonate

• insoluble Calcium Carbonate

• insoluble Calcium bicarbonate

Which of the following reaction is endothermic?

• Respiration

• Combustion of Petrol

• Photosynthesis

• Rusting of iron

When lead nitrate is heated brown fumes of a paramagnetic gas is released. Identify the gas

• O₂

• NO

• NO₂

• N₂O