English Medium Class 10 - CBSE Question Bank Solutions for Science

Write a balanced chemical equation of the following reaction and also classify them.

A piece of sodium metal is added to absolute ethanol to form sodium ethoxide and hydrogen gas.

Write a balanced chemical equation of the following reaction and also classify them.

 Iron (III) oxide on heating with carbon monoxide gas reacts to form solid iron and liberates carbon dioxide gas.

Write a balanced chemical equation of the following reaction and also classify them.

Hydrogen sulphide gas reacts with oxygen gas to form solid sulphur and liquid water.

A magnesium ribbon is burnt in oxygen to give a white compound ‘X’ accompanied by emission of light. If the burning ribbon is now placed in an atmosphere of nitrogen, it continues to burn and forms a compound ‘Y’.

1. Write the chemical formulae of X and Y.
2. Write a balanced chemical equations when X and Y are dissolved in water.

What happens when a piece of

1. zinc metal is added to copper sulphate solution?
2. aluminium metal is added to dilute hydrochloric acid?
3.  silver metal is added to copper sulphate solution?

Also write the balanced chemical equation if the reaction occurs.

In the following circuits (Figure), heat produced in the resistor or combination of resistors connected to a 12 V battery will be

(i)	(ii)	(iii)

In an electrical circuit three incandescent bulbs A, B and C of rating 40 W, 60 W and 100 W respectively are connected in parallel to an electric source. Which of the following is likely to happen regarding their brightness?

In an electrical circuit two resistors of 2 Ω and 4 Ω respectively are connected in series to a 6 V battery. The heat dissipated by the 4 Ω resistor in 5 s will be

A child has drawn the electric circuit to study Ohm’s law as shown in Figure. His teacher told that the circuit diagram needs correction. Study the circuit diagram and redraw it after making all corrections.

In the above circuit, if the current reading in the ammeter A is 2A, what would be the value of R₁? 

A complete circuit is left on for several minutes, causing the connecting copper wire to become hot. As the temperature of the wire increases, the electrical resistance of the wire

Identify the types of reaction mentioned above. Give one example for type in the form of a balanced chemical equation.

Identify the types of reaction mentioned above. Give one example for type in the form of a balanced chemical equation.

Pooja has green eyes while her parents and brother have black eyes. Pooja’s husband Ravi has black eyes while his mother has green eyes and father has black eyes.

a. On the basis of the above given information, is the green eye colour a dominant or recessive trait? Justify your answer

b. What is the possible genetic makeup of Pooja’s brother’s eye colour?

c. What is the probability that the offspring of Pooja and Ravi will have green eyes? Also, show the inheritance of eye colour in the offspring with the help of a suitable cross.

OR

c. 50% of the offspring of Pooja’s brother are green eyed. With help of cross show how this is possible.

In a cross between red coloured and white coloured flowers, when plants with red coloured flowers of F₁ generation were self pollinated, plants of F₂ generation were obtained in which 75% of plants were with red flowers and 2.5% plants were with white flowers.

Explain the inheritance of traits in the above cross with the help of a flow chart only along with the ratio of plants obtained.

An electric motor rated 1100 W is connected to 220 V mains. Find: 

1. The current drawn from the mains,
2. Electric energy consumed if the motor is used for 5 hours daily for 6 days.
3. Total cost of energy consumed if the rate of one unit is 5.

Assertion (A): In humans, if gene (B) is responsible for black eyes and gene (b) responsible for brown eyes, then the colour of eyes of the progeny having gene combination Bb, bb or BB will be black only.

Reason (R): The black colour of the eyes is a dominant trait.