[ Question Bank ] - 2022 — Science STD 10 — Question

A salt X when dissolved in distilled water gives a clear solution which turns red litmus blue. Explain the phenomenon.

Would you place the two isotopes of chlorine, Cl - 35 and Cl - 37 in different slots because of their different atomic masses or in the same slot because their chemical properties are the same? Justify your answer.

An element A has an atomic number of 6. Another element B has 17 electrons in its one neutral atom.

1. N which groups of the periodic table would you expect to find these elements?
2. What type of bond is formed between A and B?
3. Suggest a formula of the compound formed between A and B.

Give the name and structural formula of one member each of the following:

1. Alkane.
2. Alkene.
3. Alkyne.
4. Cycloalkane.

The focal length of a convex lens is 20 cm. If an object of height 2 cm is placed at 30 cm from the lens, find (i) the position and nature of the Image (ii) the height of the image (iii) the magnification produced by the lens.

Remake the table taking into account relation between entries in three columns.

I	II	III
Coal	Potential energy	Wind electricity plant
Uranium	Kinetic energy	Hydroelectric plant
Water reservoir	Nuclear energy	Thermal plant
Wind	Thermal energy	Nuclear power plant

What shape are your eye-lenses:

1. When you look at your hand?
2. When you look at a distant tree?

Write the laws :
Boiling point

How has the traditional use of energy of flowing water been modified for our convenience?

Calculate the focal length of a corrective lens having power + 2.5 D.