English Medium Class 10 - CBSE Question Bank Solutions for Science

Identify the oxidising agent (oxidant) in the following reactions 

`"Pb"_3"O"_4 + 8"HCl" -> 3"PbCl"_2 + "Cl"_2 + 4"H"_2"O"`

Identify the oxidising agent (oxidant) in the following reactions

`2"Mg" + "O"_2 -> 2"MgO"`

Identify the oxidising agent (oxidant) in the following reactions

`"CuSO"_4 + "Zn" -> "Cu" + "ZnSO"_4`

Identify the oxidising agent (oxidant) in the following reactions

`"V"_2"O"_5 + 5"Ca" -> 2"V" + 5"CaO"`

Identify the oxidising agent (oxidant) in the following reactions

`3"Fe" + 4"H"_2"O" -> "Fe"_3"O"_4 + 4"H"_2`

Identify the oxidising agent (oxidant) in the following reactions.

`"CuO" + "H"_2 -> "Cu" + "H"_2"O"`

Grapes hanging on the plant do not ferment but after being plucked from the plant can be fermented. Under what conditions do these grapes ferment? Is it a chemical or a physical change?

Which among the following are physical or chemical change?

 Evaporation of petrol

Which among the following are physical or chemical change?

Burning of Liquefied Petroleum Gas (LPG)

Which among the following are physical or chemical change?

Heating of an iron rod to red hot

Which among the following are physical or chemical change?

Curding of milk

Which among the following are physical or chemical change?

Sublimation of solid ammonium chloride

During the reaction of some metals with dilute hydrochloric acid, following observations are made.

Silver metal does not show any change

Explain this observation giving suitable reason.

During the reaction of some metals with dilute hydrochloric acid, following observations are made.

The temperature of the reaction mixture rises when aluminium (Al) is added.

Explain this observation giving suitable reason.

During the reaction of some metals with dilute hydrochloric acid, following observations are made.

The reaction of sodium metal is found to be highly explosive

Explain this observation giving suitable reason.

During the reaction of some metals with dilute hydrochloric acid, following observations are made.

Some bubbles of a gas are seen when lead (Pb) is reacted with the acid.

Why do we store silver chloride in a dark coloured bottle?

Zinc liberates hydrogen gas when reacted with dilute hydrochloric acid whereas copper does not. Explain why?

A silver article generally turns black when kept in the open for a few days. The article when rubbed with toothpaste again starts shining.

1.  Why do silver articles turn black when kept in the open for a few days? Name the phenomenon involved.
2. Name the black substance formed and give its chemical formula.

What happens when zinc granules are treated with dilute solution of H₂SO₄, HCl, HNO₃, NaCl and NaOH Also write the chemical equations if reaction oçcurs.