# CBSE Half Yearly Sample Paper 2020 Science for class 10

#### CBSE Half Yearly Sample Paper 2020 Science for class 10

Class-X

Subject: Science

Time allowed: 3 hours

Max Marks:80

All questions are compulsory.

Section-A (Physics)

1- Multiple Choice Questions.(3)

i) The unit for measuring potential difference is:

a) watt

b) ohm

c) volt

d) kWh

ii) At the time of short circuit the current in the circuit :

a) Reduces substantially

b) does not change

c) increases heavily

d) varies continuously.

iii) solar cells are made of:

a) conductors

b) insulators

c) semiconductor

d) superconductor

2- Very short answer type questions.(3)

i) What type of reflector is used in a box type solar cooker?

ii) Give the symbol of an electric fuse used is in circuit diagrams.

iii) Name two effects produced by electric current.

i) An electric bulb of resistance 20 ohm and a resistance wire of 4 ohm are connected in series with a 6 volt battery. Draw the circuit diagram and calculate:

a) Total resistance of the circuit

b) current through the circuit

c) potential difference across the electric bulb.

ii) Two resistances when connected in parallel give resultant value of 2 ohm, when connected in series the value becomes 9 ohm calculate the value of each resistance.

iii- a) What is a solenoid? Draw a sketch to show the magnetic field pattern produced by a current carrying solenoid.

iii- b) Name the type of magnet with which the magnetic field pattern of current carrying solenoid resemble.

iv- a) With the help of a labelled diagram explain the construction and working of a solar cooker.

iv- b) Why the solar cooker box is painted black from inside?

i) A nuclear reaction is represented by the following equation : 92U235 +0n1  ➡56 Ba 139 +36 Kr94 +xc+E

a) Name the process represented by this equation and describes what takes place in this reaction.

b) Identify the particle c and the number x of a particle is produced in the reaction.

c) What does E represent?

d) Name one installation where the above nuclear reaction is utilized.

e) What type of bomb is based on similar type of reaction?

a) What do you understand by the term electromagnetic induction? Explain with the help of diagram.

b) Name one device which works on the phenomenon of electromagnetic induction.

c) Describe different ways to induce current in a coil of wire.

Section-B (Chemistry)

1- Multiple choice Questions.(3)

i) Which of the statements about the reaction are incorrect? 2PbO +C  ➡ 2Pb +CO2

I-Led is getting reduced

II- carbon dioxide is getting oxidized

III- carbon is getting oxidised

IV- led oxide is getting reduced

a) I and II

b) I and III

c) I,II,III

d) all

ii) A solution reacts with crushed egg -shells to give a gas that turns lime water milky.The solution contains:

a) NaCl

b) HCl

c) LiCl

d) KCl

iii) The atomic no. Of an element X is 19.The number of electron in its Ion X+ will be:

a) 18

b) 19

c) 20

d) 21

2- Very short answer type questions.  4

i) What type of chemical reaction takes place when silver bromide is exposed to sunlight?

ii) Which is more acidic solution of pH=2 or a solution pH=6?

iii) State two ways to prevent the rusting of iron.

iv) The atomic number of sodium is 11. What is the number of electrons in sodium ion?

3- Short answer type questions. (Do any 3 out of 5)(9)

i) Why decomposition reactions are called the opposite of combination reactions? Explain with the help of one example each.

ii) What happens during a bee sting? What is its remedy?

iii) What happens when a cold and concentrated solution of sodium chloride reacts with Ammonia and carbon dioxide? Write the chemical equation of the reaction which takes place.

iv) Why is sodium kept immersed in kerosene oil and white phosphorus kept immersed in water?

v) Draw the electron-dot structures of the following compounds and state the type of bonding in each case:

a) KCl

b) NH3

c) N2

4- Long answer type questions.(Do any 2 out of 3)(10)

i)

a) What is plaster of Paris? Write the chemical formula of plaster of Paris.

b) How is plaster of Paris prepared write chemical equation of the reaction involved?

c) State two important use of plaster of Paris.

ii)

a) What are metals? Name five metals.

b) Name a metal which is so soft that it can be cut with a knife.

c) Name the metal which is the best conductor of heat and electricity.

d) Name a non metal which conducts electricity.

e) Name a non metal which is extremely hard.

iii) Which metal is extracted from bauxite ore? Describe the extraction of zinc metal from its sulphide Ore (zinc blende). Write equations of the reactions involved.

Section-C (Biology)

1- Multiple choice Questions.(4)

i) Which one of the following is not a part of the human male reproductive system?

a) Oviduct

b) Seminal vesicle

c) testes

d)prostate gland

ii) An alga which reproduces by the fragmentation is called –

a) Rhizopus

b) Spirogyra

c) Salmonalla

d) Paramecium

iii) One of the following acts as a mixed gland, this is –

a) Salivary gland

b) Pitatary

c)Thyroid

d)pancrease

iv) The largest gland in human body is-

a) Pituitary

b) Liver

c)Pancreases

d)salivary gland

2- Photo synthesis converts the energy S into C. What are S and C stand for.(1)

3- Veins and arteries carry blood. Which of these carry blood- (1)

i) To the organs

ii)to the heart

iii) to the all parts of body

4- Name the male and female reproductive part of flower.(1)

a) What is done in contraception method known as-

i) Tubectomy

ii)  vasectomy

b) What is formed when male and female gamates are fused?

c) What are the male sex cells are called.

6- Match the harmones given in columm A write the glands given in columm B.(3)

A                                             B

Estrogen                                     Pitutary

Growth hormone                     Testes

Testorteron                              ovary

Thyroid                                    Pancrease

7- How and where are oxygen and carbon dioxide exchanged in our body during respiration?

Or

Write the chemical equation representing aerobic and anaerobic respiration.

8-

i) Explain the following movements in plants with suitable examples.(3)

a) Phototropic

b) Geotropic

c) Thigmonastics

ii) Draw a labbled diagram of nouron or nervecell. 2

9- Describes the structure of human blood in detail. 5

Or

i) What is vegetative propagation? Explain tissue culture and its advantages. 2

ii) Draw a neat and well lablled diagram of female reproductive system of human. 3