Science Class 10 chapter 1 chemical reactions and equations

A chemical reaction has taken place in which of the following process?

• (i) Ice melts into water

• (ii) A wet shirt got dried in sunlight

• (iii) A brown layer is formed over iron rod kept in air

• (iv) Sugar getting dissolved in water

Tags

NGSS.HS-PS1-2

A chemical reaction has taken place can be represented by which of the following condition?

• (i) Evolution of gas

• (ii) Heat released

• (iii) Change in color

• (iv) All the above

A chemical equation is said to be balanced if number of

• (i) Compounds are same in both side

• (ii) Molecules are same in both side

• (iii) Number of atoms is same in both side

• (iv) Number of electrons are same in both side

Tags

NGSS.HS-PS1-7

Write values of a,b and c if following chemical reaction is balanced .

aMg + bO2 → cMgO

• (i) a=2, b=1, c=2

• (ii) a=1, b=1, c=2

• (iii) a=2, b=1, c=1

• (iv) a=2, b=2, c=2

Tags

NGSS.HS-PS1-7

Which of the following reactions satisfies this condition? :

Iron nails kept with dilute sulphuric acid and ferric sulphite solution is formed and hydrogen gas is released.

• (i) 2Fe(s) + 3H2 SO4(l)→ Fe2 (SO4)3(l) + 3H2(g)

• (ii) 2Fe(s) + 2H2SO4(aq) → Fe2(SO4)3(s) + 4H2 (g)

• (iii) 2Fe(s) + 2H2SO4 (aq) → 3Fe2(SO4)3(aq) + 2H2(g)

• (iv) 2Fe(s)+3H2SO4 (aq) → Fe2(SO4)3 (aq) + 3H2 (g)

Tags

NGSS.HS-PS1-2

NGSS.HS-PS1-7

Calcium oxide reacts with water to form calcium Hydroxide. Which type of reaction is this?

• (i) Combination and endothermic reaction

• (ii) Combination and exothermic reaction

• (iii) Decomposition and Endothermic reaction

• (iv) Decomposition and exothermic reaction

Tags

NGSS.HS-PS1-4

On thermal decomposition of lead nitrate, nitrogen dioxide gas is evolved. How it presence can be verified?

• (i) It will turn lime water milky

• (ii) Rotten egg odour

• (iii) Brown fumes can be observed

• (iv) Reddish fume is observed

The chemical formula of lead sulphate is

• (a) Pb2SO4

• (b) Pb(SO4)2

• (c) PbSO4

• (d) Pb2(SO4)3

Chemically rust is

• (a) hydrated ferrous oxide

• (b) only ferric oxide

• (c) hydrated ferric oxide

• (d) none of these

Tags

NGSS.HS-PS1-1

The electrolytic decomposition of water gives H2 and O2 in the ratio of :

• (a) 1 : 2 by volume

• (b) 2 : 1 by volume

• (c) 8 : 1 by mass

• (d) 1 : 2 by mass

Tags

NGSS.HS-PS1-7