English Medium इयत्ता १० - CBSE Question Bank Solutions for Science

The defect of vision in which the person is able to see a distant object distinctly but cannot see nearby objects clearly is called:

Assertion: The near point of a hypermetropia eye is more than 25 cm away.

Reason: Hypermetropia is corrected using spectacles containing concave lenses.

Graphite is used as a lubricant in machines because ______.

The allotrope of carbon which is a good conductor of heat and electricity is ______.

Lead pencil contains ______.

From which of the following substance pencil lead is formed?

Which of the following oxide(s) of iron would be obtained on prolonged reaction of iron with steam?

Silver articles become black on prolonged exposure to air. This is due to the formation of

Stainless steel is very useful material for our life. In stainless steel, iron is mixed with

If copper is kept open in air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of

When a metal X is treated with cold water, it gives a basic salt Y with molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z and also write the reaction involved.

Draw ray diagram showing hypermetropic eye.

The metal which produces hydrogen gas on reaction with dilute hydrochloric acid as well as sodium hydroxide solution is ______.

Keerti added dilute Hydrochloric acid to four metals and recorded her observations as shown in the table given below:

Select the correct observation(s) and give chemical equation(s) of the reaction involved.

Metal oxides generally react with acids, but few oxides of metal also react with bases. Such metallic oxides are:

1. MgO
2. ZnO
3. Al₂O₃ 
4. Cao

Select the appropriate state symbols of the products given as X and Y in the following chemical equation by choosing the correct option from table given below: 

\[\ce{Zn_{(s)} + H_2SO_{4(l)} ->ZnSO_{4(X)} + H_{2(Y)}}\]

List two difference in the characteristic properties of the virtual images formed by the two types of spherical lenses (concave and convex). How are these characteristics of the two lenses use in the correction of the two common defects of vision namely myopia and hypermetropia?

Write a chemical equation showing the ionic products formed on dissolving potassium hydroxide in water.

On adding dilute sulphuric acid to a test tube containing a metal ‘X’, a colourless gas is produced when a burning match stick is brought near it. Which of the following correctly represents the metal ‘X’?

Why is the amount of gas collected in one of the test tubes in the following Activity double of the amount collected in the other? Name this gas.

• Take a plastic mug. Drill two holes at its base and fit rubber stoppers in these holes. Insert carbon electrodes in these rubber stoppers as shown in the following Fig.
• Connect these electrodes to a 6 volt battery.
• Fill the mug with water such that the electrodes are immersed. Add a few drops of dilute sulphuric acid to the water.
• Take two test tubes filled with water and invert them over the two carbon electrodes.
• Switch on the current and leave the apparatus undisturbed for some time.
• You will observe the formation of bubbles at both the electrodes. These bubbles displace water in the test tubes.
• Is the volume of the gas collected the same in both the test tubes?
  • Once the test tubes are filled with the respective gases, remove them carefully.
• Test these gases one by one by bringing a burning candle close to the mouth of the test tubes.

Caution: This step must be performed carefully by the teacher.

• What happens in each case?
• Which gas is present in each test tube?