Structure of the Atom — Science STD 9 — Question

A liquid compound X of molecular mass 18u can be obtained from a number of natural sources. All the animals and plants need liquid X for their survival. When an electric current is passed through 200 grams of pure liquid X under suitable conditions, then 178 grams of gas Y and 22 grams of gas Z are produced. Gas Y is produced at the positive electrode whereas gas Z is obtained at the negative electrode. Moreover, gas Y supports combustion whereas gas Z burns itself causing explosions.

1. Name (i) liquid X (ii) gas Y, and (iii) gas Z
2. What is the ratio to the mass of element Z to the mass of element Y in the liquid X?
3. Which law of chemical combination is illustrated by this example?
4. Name two sources of liquid X.
5. Gate an important use of Y in our life.

The atom of an element X contains 17 protons, 17 electrons and 18 neutrons whereas the atom of an element Y contains 11 protons, 11 electrons and 12 neutrons.

1. What type of ion will be formed by an atom of element X? Write the symbol of ion formed.
2. What will be the number of (i) protons (ii) electrons, and (iii) neutrons, in the ion formed from X?
3. What type of ion will be formed by an atom of element Y? Write the symbol of ion formed.
4. What will be the number of (i) protons (ii) electrons, and (iii) neutrons, in the ion formed from Y?
5. What is the atomic mas of (i) X, and (ii) Y?
6. What could the elements X and Y be?

Which of the following are matter?
Chair, air, love, smell, hate, almonds, thought, cold, lemon water, smell of perfume.

Iron powder and sulphur powder were mixed together and divided into two parts A and B. When part A was heated strongly over a burner, then a substance C was formed. The part B was, however, not heated at all. When dilute hydrochloric acid was added to substance C, then gas D was evolved and when dilute hydrochloric acid was added to part B then gas E was evolved.

1. What type of substance is B?
2. What type of substance is C?
3. Name the gas (i) D, and (ii) E?
4. Write one characteristic property of gas D.

There is a large group of materials P which can be divided into three groups Q, R, and S on the basis of their properties. The substances belonging to group Q can be solids, liquids or gases. The solids belonging to group Q are usually electrical insulators. Most of the substances of group R are solids which are good conductors of electricity. The substances belonging to group S are neither insulators like Q nor good conductors like R. The properties of S are intermediate between those of Q and R.

1. What could the group of materials P be?
2. Name the substances Q. Give two examples of such substances.
3. Name the substances R. Write two examples of such substances.
4. Name the substances S. Give two examples of such substances.
5. Out of Q, R and S, which substances are malleable and ductile?

State the main points of difference between homogeneous and heterogeneous mixtures.

How will you separate camphor, common salt and iron nails from their mixture?

There is a large group of materials P which can be divided into three groups Q, R, and S on the basis of their properties. The substances belonging to group Q can be solids, liquids or gases. The solids belonging to group Q are usually electrical insulators. Most of the substances of group R are solids which are good conductors of electricity. The substances belonging to group S are neither insulators like Q nor good conductors like R. The properties of S are intermediate between those of Q and R.

1. What could the group of materials P be?
2. Name the substances Q. Give two examples of such substances.
3. Name the substances R. Write two examples of such substances.
4. Name the substances S. Give two examples of such substances.
5. Out of Q, R and S, which substances are malleable and ductile?

Look at the diagram on the right side. Jar A contains are d-brown gas whereas Jar B contains a colourless gas. The two gas jars are separated by a glass plate placed between them:

1. What will happen when the glass plate between the two jars is pulled away?
2. What name is given to the phenomenon which takes place?
3. Name the brown gas which could be in jar A.
4. Which is the colorless gas most likely to be present in jar B?
5. Name one coloured solid and one colourless liquid which can show the same phenomenon.

Fill in the missing data in the following table.

SpeciesProperty	H2O	CO2	Na atom	MgCl2
No. of moles	2	—	—	0.5
No. of particles	—	3.011 × 1023	—	—
Mass	36g	—	115g	—