6th Std Practical Class 2 – Some important questions and answers

Pencil and Wire

Q1. Find the thickness of the given wire.

• Thickness of 10 windings = 1.6 cm = 16 mm (depends on the wire you use)

• So, thickness of the wire = 0.16 cm = 1.6 mm

Q 2. Find the circumference of the pencil.

• Length of 10 windings = 28.5 cm

• So, circumference of the pencil = 2.85 cm

Mirrors at an angle

Angle between mirrorsNumber of Images

2. What relation do you see between the angle and the number of images?
As angle decreases, number of images increases

* 3. For which angle do you see exactly 4 images?
72 degrees

4. How many images will be formed if the object is kept between two parallel mirrors?
infinitely many

Identify Metal Cubes

1.Brass is an alloy of copper and zinc

2.Bronze is an alloy of copper and tin

3.Write symbols for
  Lead – Pb
  Iron – Fe
  Tin – Sn
  Copper – Cu

Area and Perimeter of L shape

1. Area = 48 sq cm, Perimeter = 32 cm

2. Perimeter will increase by 4 cm. Area will decrease by 4 sq cm

Red and Blue Gelatin papers

Q1. Observe through RED gelatin paper —

  a) Which words can you read?

  ‘BLUE’ and ‘BLACK’

  b) Which colour do they appear?

  They both appear Black.

Q2. Observe through BLUE gelatin paper —

  a) Which words can you read?

  ‘RED’ and ‘BLACK’

  b) Which colour do they appear?

  They both appear Black.

Q3. Now observe the words through both the gelatin papers together. Which words can you read?

None of them

Q4. Observe white paper through both the gelatins. What do you observe?

White paper appears red through red gelatin and blue through blue gelatin paper

Q5. Are black and white basic colours?
If not, what colours are they made up of?

No. Black is absence of light and white is a mixture of all 7 colours

Q6. Which coloured light can pass through red gelatin paper? — Red

Q7. Why can we not read the word “RED” through red gelatin paper?

Because the background and the word both appear red So we cannot distinguish the letters from the background.

Q8. Why does the word “BLUE” appear black when seen through red gelatin paper?

The blue colour reflected from the word “Blue” cannot pass through the red gelatin. As no light reaches our eye from that part, it appears black.

Volume of Cuboid by calculation and measuring

1. New water level = 65 cc

2. Volume of eraser = 65 – 50 = 15 cc

3. Dimensions:

  Length = 6.1 cm

  Breadth = 2.1 cm

  Height = 1.1 cm

4. Formula for volume of cuboid
  = Length x Breadth x Height

5. Volume of the eraser = 6.1 x 2.1 x 1.1 = 14 cu cm

6. We see that the two answers are almost equal.

Try at Home –

Find the volume of the prism in your kit.

Soda-Bi-Carb + Citric Acid

Q1. Does any reaction take place when the mixture is dry? Why?

No. Water is an essential medium for reaction

Q2. What do you observe when water is added?

We see bubbles (effervescence) and the blue litmus turns red.

Q3. What can you conclude from this?

The gas which has evolved is acidic in nature

Q4. Which gas evolves?

Carbon-dioxide – CO2

Q5. Write 2 uses of this gas. 

Fire extinguishers, dry ice

Q6. Write 2 chemical properties of this gas.

acidic, does not support burning

Q7. Write 2 physical properties of this gas.

colourless, odourless

Q8. What will happen to a lighted candle when taken near the gas?

It will get extinguished.

Overflow Vessel

  1. What was the volume of the stone? — 72cc

2. What will be the mass of this stone if its density is 2.5 gm/cc?

Mass = Density x Volume =   = 2.5 gm/cc x 72 cc = 180 gm

3. Will the accuracy of the answer change if pour the water into a beaker of the same capacity (100 cc) instead of the measuring cylinder?

Yes, because the least count of the measuring cylinder is smaller

Try at home

Make an overflow vessel and find volume and density of a potato.

Separate Salt and Ammonium Chloride

1.What did you observe?
White fumes are observed. And sides of the test tube are deposited with white colour substance.

Ammonium chloride is a sublimable substance. On heating it becomes fumes (gas) and on cooling it again becomes solid.

3.Chemical formula of ammonium chloride

4.Uses of ammonium chloride
dry cells, fertilizers

Ice Cubes Activity (Regelation)

  1. What did you observe when the ice cubes were pressed together? Why does this happen?

The cubes got joined to each other. As pressure is applied, the melting point of ice drops and the ice at the touching surface of the cubes, melts. When pressure is removed, the melting point again rises and the water at the touching surface again solidifies joining the cubes together.

2. How is the wire able to pass through the ice block without cutting it?

The wire applies pressure on the ice. So the melting point of this ice drops and it melts. So wire passes down. Now pressure on the top ice is gone, so it again solidifies.

3. In a pressure cooker, due to high pressure:
Boiling point of water increases.

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