English Medium Class 10 - CBSE Question Bank Solutions for Science

What would be the effect on the resistance of a metal wire of:  

increasing its temperature?

How does the resistance of a wire change when: 

its material is changed to one whose resistivity is three times?

Calculate the area of cross-section of a wire if its length is 1.0 m, its resistance is 23 Ω and the resistivity of the material of the wire is 1.84 × 10⁻⁶ Ω m.

The figure blow shows a variable resistor in a dimmer switch.  

How would you turn the switch to make the lights: (a) brighter, and  (b) dimmer? Explain your answer. 

The back face of a circular loop of wire is found to be south magnetic pole. The direction of current in this face of the circular loop of wire will be: 

(a) towards south
(b) clockwise
(c) anticlockwise
(d) towards north 

State two characteristics of the chemical reaction which takes place when dilute sulphuric acid is poured over zinc granules.

Why does the colour of copper sulphate solution change when an iron nail is kept immersed in it?

What type of chemical reaction is represented by the following equation?

A + BC → AC + B

What type of chemical reaction is represented by the following equation?

A₂O₃ + 2B → B₂O₃ + 2A

what type of reaction is the following:

Cl₂ + 2KI → 2KCl + I₂ 

What type of reaction is represented by the following equation?

2Na + 2H₂O → 2NaOH + H₂

What type of reaction is represented by the following equation?

Mg + CuSO₄ → MgSO₄ + Cu

What is meant by displacement reaction, Explain with help of one example.

What happens when a piece of iron metal is placed in copper sulphate solution? Name the type of reaction involved.

What happens when a zinc strip is dipped into a copper sulphate solution?
Write the equation for the reaction that takes place.

What happens when a zinc strip is dipped into a copper sulphate solution?
Name the type of reaction involved.

A strip of metal X is dipped in a blue coloured salt solution YSO₄. After some time, a layer of metal Y from the salt solution is formed on the surface of metal strip X. Metal X is used in galvanisation whereas metal Y is used in making electric wires. Metal X and metal Y together form an alloy Z.
(a) What could metal X be?
(b) What could metal Y be?
(c) Name the metal salt YSO₄.
(d) What type of chemical reaction takes place when metal X reacts with salt solution YSO₄? Write the equation of the chemical reaction involved.
(e) Name the alloy Z.

When a black metal compound XO is heated with a colourless gas Y₂, then metal X and another compound Y₂O are formed. Metal X is red-brown in colour which does not react with dilute acids at all. Gas Y₂ can be prepared by the action of a dilute acid on any active metal. The compound Y₂O is a liquid at room temperature which can turn anhydrous copper sulphate blue.
(a) What do you think is metal X?
(b) What could be gas Y₂?
(c) What is compound XO?
(d) What is compound Y₂O?
(e) Write the chemical equation of the reaction which takes place on heating XO with Y₂.
(f) What type of chemical reaction is illustrated in the above equation?

When a strip of red-brown metal X is placed in a colourless salt solution YNO₃ then metal Y is set free and a blue coloured salt solution X(NO₃)₂ is formed. The liberated metal Y forms a shining white deposit on the strip of metal X.
(a) What do you think metal X is?
(b) Name the salt YNO₃.
(c) What could be metal Y?
(d) Name the salt X(NO₃)₂.
(e) What type of reaction takes place between metal X and salt solution YNO₃?