chemical reactions and equations

when does a chemical reaction take place ?

• when a physical change occurs

• when a chemical change occurs

• both a and b

• none of the above

What are the substances on the left side called and right side of the chemical equation called respectively ?

• products and reactants

• groups and electrons

• nothing

• reactants and products

Which of the following is not a physical change?

• (a) Boiling of water to give water vapour

• (b) Melting of ice to give water

• (c) Dissolution of salt in water

• (d) Combustion of Liquefied Petroleum Gas (LPG)

Which of the following statements about the given reaction are correct?

3Fe_(s) + 4H₂O_(g) => Fe₃O_4(s) + 4H_2(g)

(i) Iron metal is getting oxidised

(ii) Water is getting reduced

(iii) Water is acting as reducing agent

(iv) Water is acting as oxidising agent

• (a) (i), (ii) and (iii)

• (b) (iii) and (iv)

• (c) (i), (ii) and (iv)

• (d) (ii) and (iv)

which of the following observations helps to determine that a chemical reaction has taken place ?

• change in state

• change in color

• change in temperature

• all of the above

A solution of X is used for white washing walls. it reacts slowly with Y in air to form a thin layer of B on walls which gives walls a shiny finish. which of the following options correctly represents X,Y and B ?

• X =slaked lime , Y = nitrogen , B=calcium oxide

• X =Calcium Hydroxide, Y=Oxygen, B = Calcium carbonate

• X= slaked lime, Y=Carbon oxide,B= calcium chloride

• X= slaked lime,Y=Carbon dioxide,B=Calcium carbonate

What is the process that is happening in this image ? And also give the name of the two gas that are present in two test tubes and the ratio they(gases) are present in .

• process= thermal decomposition,

  gases present=hydrogen,carbon dioxide, ratio=2:1

• process=corrosion,

  gases present=oxygen,hydroxide, ratio=2:1

• process=electrolysis of hydrogen polyoxide

  gases present=hydrogen,oxygen, ratio=2:1

• process=electrolysis of water

  gases present=hydrogen,oxygen,ratio=4:2

Choose the correct balanced equation of barium chloride and aluminium sulphate.

• 3BaCl2+Al2(SO4)3→3BaSO4+2AlCl3

• 2BaCl2+Al2(SO4)3→2BaSO4+2AlCl3

• 6BaCl2+2Al2(SO4)3→6BaSO4+4AlCl3

• none of the above

Choose the incorrect statement from the following options about saving foods from rancidity.

• keep food items in air tight containers

• flushing food items with carbon dioxide

• flushing food items with nitrogen

• keep food items in air loose containers

The following reaction is an example of a 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g)(i) displacement reaction (ii) combination reaction (iii) redox reaction (iv) neutralisation reaction

• (i) and (iv)
• (ii) and (iii)
• (i) and (iii)
• (iii) and (iv)