10 Science Solved Sample Paper 1

Section E

Question: 22. A students performed the experiment of heating ferrous sulphate crystals in a boiling tube He felt fumes of a pungent gas and saw colors of ferrous sulphate disappeared. [2]
(1). Write the chemical formula of the pungent gases.
(2). Why does the colour of crystal disappear?
(3). Identify the nature of this chemical reaction.

Answer:

1. These pungent gases are SO₂ and SO₃.
2. Ferrous sulpuate crystals changed to Ferric oxide compound.
3. This is a Thermal (Heat) decomposition reaction.

Or
What type of material is formed when aqueous solutions of sodium sulphate and barium chloride are mixed. Give the balanced chemical equation involved. Name the type of reaction it is?

Question: 23. In the experiment which verifies the Ohm’s Law, where should the: [2]
(1). ammeter and
(2). voltmeter be connected?

Answer:

1. Ammeter should be connected in series after the experiment wire.
2. Voltmeter should be connected in parallel between the two ends of the experiment wire.

Question: 24. A student prepared a temporary mount of a leaf peel and observed some green dots. [2]
(1). Name these green dots and name the pigment present in them.
(2). State the function of this pigments.

Answer:

1. These green dots are chloroplasts. Chlorophyll pigment is present in them.
2. This pigment is the site of photosynthesis in the leaves of the green plants.

Question: 25. A student studies the properties of acetic acid in his school laboratory. List two physical properties of acetic acid he would observe. Write two observations of the reaction that occurs when he adds a pinch of sodium bicarbonate powder to 5 ml acetic acid taken in a test-tube. [2]

Answer: Two physical properties:

1. It is a colourless liquid;
2. It has a pungent odour like vinegar.

Two observations:

1. A gas with brisk effervescence is evolved;
2. Lime water turns milky when this gas is passed through it.

Question: 26. To illustrate the process of binary fission in Amoeba, draw diagrams of various stages of this process in the correct sequence. [2]

Question: 27. Draw a diagram to trace the path of a ray light incident at an angle of 40° on a rectangular glass slab. Write the measure of the angle of refraction and angle of emergence. [2]

Hints: ∠r = less than 40°/28° – 30°; ∠e = 40°

Or
To construct a ray diagram, we use two light rays which are so chosen that it is easy to know their directions after refraction from the convex lens. List these two rays and state the path of these rays after refraction.