Acids, Bases and Salts — Science STD 10 — Question

a. Explain the surgical method of contraception used by (i) males, and (ii) females to prevent fertilisation.
b. Write the role of oral pills taken by women as a contraceptive.

What is the difference between a cation and an anion? How are they formed? Give the names and symbols of one cation and one anion.

The calorific values of three fuels A, B and C are 33kJ/ g, 48kJ/ g and 150kJ/ g, respectively. A is solid, B is liquid and C is a gas at room temperature. One combustion, both A and B produce carbon dioxide while C explodes forming steam. B and C leave no residue after combustion while A leaves behind some solid residue. Which one of the three fuels is the most ideal? Give two reasons to support your answer.

Taking the example of an element of atomic number 16, explain how the electronic configuration of the atom of an element relates to its position in the modern periodic table and how valency of an element is calculated on the basis of its atomic number.

The refractive indices 1.0003, 1.31 1.5 respectively of Air, Ice and Benzine in which of these does the light travels fastest?

Two elements X and Y belong to group1 and 2 respectively in the same period of periodic table. Compare them with respect to:

1. The number of valence electrons in their atoms.
2. Their valencies.
3. Metallic character.
4. The sizes of their atoms.
5. The formulae of their oxides.
6. The formulae of their chlorides.

State where an object must be placed so that the image formed by a concave mirror is:

1. Erect and virtual.
2. At infinity.
3. The same size as the object.

Give the formulae of the chlorides of the elements X and Y having atomic numbers of 3 and 6 respectively. Will the properties of the two chlorides be similar or different? Explain your answer:

What is the minimum number of rays required for locating the image formed by a concave mirror for an object? Draw a ray diagram to show the formation of a virtual image by a concave mirror.