English Medium कक्षा १० - CBSE Question Bank Solutions for Science

An electric kettle consumes 1 kW of electric power when operated at 220 V. A fuse wire of what rating must be used for it?

B₁, B₂ and B₃ are three identical bulbs connected as shown in Figure. When all the three bulbs glow, a current of 3A is recorded by the ammeter A.

1.  What happens to the glow of the other two bulbs when the bulb B₁ gets fused?
2. What happens to the reading of A₁, A₂, A₃ and A when the bulb B₂ gets fused?
3. How much power is dissipated in the circuit when all the three bulbs glow together?

Three incandescent bulbs of 100 W each are connected in series in an electric circuit. In another circuit another set of three bulbs of the same wattage are connected in parallel to the same source.

1. Will the bulb in the two circuits glow with the same brightness? Justify your answer.
2. Now let one bulb in both the circuits get fused. Will the rest of the bulbs continue to glow in each circuit? Give reason.

A carbon compound ‘A’ having melting point 156K and boiling point 351K, with molecular formula C2H6O is soluble in water in all proportions.

1. Identify ‘A’ and draw its electron dot structure.
2. Give the molecular formulae of any two homologues of ‘A’.

It would cost a man Rs. 3.50 to buy 1.0 kW h of electrical energy from the Main Electricity Board. His generator has a maximum power of 2.0 kW. The generator produces energy at this maximum power for 3 hours. Calculate how much it would cost to buy the same amount of energy from the Main Electricity Board.

A student boils water in an electric kettle for 20 minutes. Using the same mains supply he wants to reduce the boiling time of water. To do so should he increase or decrease the length of the heating element? Justify your answer.

Two students decided to investigate the effect of water and air on iron object under identical experimental conditions. They measured the mass of each object before placing it partially immersed in 10 ml of water. After a few days, the object were removed, dried and their masses were measured. The table shows their results.

What might be the reason for the varied observations of the two students?

In which of the following applications of Iron, rusting will occur most? Support your answer with valid reason.

A	B	C	D

In a set up the students coated iron nails with zinc metal and noted that, iron nails coated with zinc prevents rusting. They also observed that zinc initially acts as a physical barrier, but an extra advantage of using zinc is that it continues to prevent rusting even if the layer of zinc is damaged. Name this process of rust prevention and give any two other methods to prevent rusting.

An electric kettle consumes 1 kW of electric power when operated at 220 V. A fuse wire of what rating must be used for it?

An electric kettle of 2 kW is used for 2h. Calculate the energy consumed in 

1. kilowatt hour and
2. joules.

Write the chemical formula of two consecutive homologous of organic compounds having functional group - OH. 

What happens to the (i) boiling point and (ii) solubility of organic compounds of a homologous series as the molecular mass increases?

What is the heating effect of electric current?

Write an expression for the amount of heat produced in a resistor when an electric current is passed through it stating the meanings of the symbols used.

Consider the carbon compounds having following molecular formula:

(i) C₃H₆ (ii) C₃H₈ (iii) C₄H₆ (iv) C₆H₆ (v) C₆H₁₂

1. State the number of double covalent bonds present in C₃H₆.
2. Write the formula of first member of the homologous series to which the carbon compound C₄H₆ belongs.
3. Which one of the above compounds forms a ring structure of carbon atoms?
4. Identify, which of the above compounds, is a member of alkane series.

Consider the following molecular formulae of carbon compounds:

(i) CH₃COOH (ii) CH₃OH (iii) C₂H₆ (iv) C₃H₄ (v) C₄H₈ 

1. Which one of these compounds belongs to homologous series of alcohols?
2. Identify the compound having triple bond between carbon-carbon atoms.
3. Write the molecular formula of the first member of the homologous series to which CH₃COOH belongs.
4. Write the general formula of the series to which the compound C₄H₈ belongs.

Consider the carbon compounds having following molecular formula:

(i) C₂H₂ (ii) C₂H₅ (iii) C₃H₇OH (iv) C₂H₆COOH (v) CH₃CHO

1. Identify which one of the above compounds, is a member of aldehyde series.
2. Write the general formula of the series to which compound C₂H₂ belongs.
3. Which one of the above compounds has triple bonds between carbon-carbon atoms?
4. Write the molecular formula of the first member of the homologous series to which the compound C₃H₇OH belongs.