English Medium कक्षा १० - CBSE Question Bank Solutions for Science

Consider the following salts:

Na₂CO₃, NaCl, NH₄Cl, CH₃COONa, K₂SO₄, (NH)₂SO₄

Which of these salts will give:

1. acidic solutions?
2. neutral solutions?
3. basic solutions (or alkaline solutions)?

Write the name and formula of one salt which contains:

Two molecules of water of crystallisation.

Write the name and formula of one salt which contains:

Five molecules of water of crystallisation.

How many molecules of water of crystallisation (per formula unit) are present in:

Copper sulphate crystals

Define the following:

Reflex arc

You are asked to prepare hard water in your laboratory. Select a group from the following groups of salts, any salt of which you may dissolve in distilled water to obtain hard water.
(A) NaCl; Na2SO4; KCl
(B) NaCl; CaCl2; KCl
(C) CaCl2; CaSO4; MgSO4
(D) Na2SO4; CaSO4; MgSO4

Hard water required for an experiment is not available in a school laboratory. However, following salts are available in the laboratory. Select the salts which may be dissolved in water to make it hard for the experiment.

(A) 1, 2 and 4

(B) 1, 3 and 6

(C) 3, 5 and 6

(D) 2, 4 and 5

Nervous and hormonal systems together perform the function of control and coordination in human beings. Justify this statement with the help of an example.

Answer the following question.
While studying the dependence of potential difference ( V) across a resistor on the current (I) passing through it, in order to determine the resistance of the resistor, a student took 5 readings for different values of current and plotted a graph between V and t. He got a straight line graph passing through the origin. What does the straight-line signify? Write the method of determining the resistance of the resister using this graph. 

Two bulbs of 100 W and 40 W are connected in series. The current through the 100 W bulb is 1 A. The current through the 40 W bulb will be ______.

Name the parts (a) to (e) in the following diagram.

What is the term given to the sequence of events occurring in the diagram?

Plants do not have any nervous system but yet, if we touch a sensitive plant, some observable changes take place in its leaves. Explain how could this plant respond to the external stimuli and how it is communicated.

Sodium carbonate is a basic salt because it is a salt of a ____________.

Which of the following is not an acidic salt?

Many salts absorb water from the atmosphere. This property is called:

Two wires of the same length and area made of two materials of resistivity ρ₁ and ρ₂ are connected in series to a source of potential V. The equivalent resistivity for the same area is:

If R₁ and R₂ be the resistance of the filament of 40 W and 60 W respectively operating 220 V, then:

The resistance of the hot filament of the bulb is about 10 times the cold resistance. What will be the resistance of 100 W-220 V lamps, when not in use?

What is the maximum resistance which can be made using five resistors each of `1/5` W?