Science MCQ

Science MCQ

Exam Portions

Lessons

4 Heat

6 Physical and Chemical Changes

10 Respiration in Organisms

11 Transportation in Plants and Animals

12 Reproduction in Organisms

13 Motion and Time

14 Electric Current and its Effects

15 Light

Multiple Choice

1. We feel more comfortable with dark coloured clothes during winter because

• Dark coloured clothes are very cool

• Dark coloured clothes reflects more heat

• Dark coloured clothes looks good

• Dark colured clothes absorbs more heat

Explanation

 Dark coloured clothes absorbs more heat than light coloured clothes to keep our body warm so, we feel more comfortable wearing dark coloured clothes during winter.While light coloured clothes reflects most of the heat that falls on them, so we feel comfortable wearing them in summer

Multiple Choice

2. Conduction is the method of transfer of heat in:

• Liquids

• Vacuum

• Solids

• Gases

Explanation

In solids, heat travels from the hotter end of the body to the colder end with the method of conduction.

Multiple Choice

3. Boiling point of pure water at sea levels is ______ degree F.

• 312

• 98

• 112

• 212

Explanation

Boiling point of pure water at sea level is 212 degree Fahrenheit and 100 degree Celsius. 

Multiple Choice

4. In summer, people paint their cars with silver color in order to prevent

• release of heat

• absorption of heat

• transfer of heat

• strength of heat

Explanation

 absorption of heat

Multiple Choice

5. Which kind of clothes will you prefer most in summers?

• Thin clothes with white colour

• Thin clothes with black colour

• Thick clothes with white colour

• Thick clothes with black colour

Explanation

Thin clothes with white colour absorbs least of the sun rays and will keep us cool in summers

Multiple Choice

6. Heat from sun reaches us by:

• Conduction

• Convection

• Radiation

• Evaporation

Explanation

The sun heats the earth through radiation. Since there is no medium (like the gas in our atmosphere) in space, radiation is the primary way through which heat travels in space. 

Multiple Choice

7. Which of the following statement is true for a physical change?

• It change a substance into different substance

• It alters the form and appearance of the substance

• More than one substance must be present

• Burning is an example

Explanation

In physical changes the form and appearance of the substance changes temporarily which can be reversed back.

Multiple Choice

8. When water freezes it undergoes a

• Vaporisation

• Sublimation

• Physical change

• Chemical change

Explanation

When water freezes it undergoes a physical change since no new substance is formed.

Multiple Choice

9. Which of the following may not be followed by a chemical reaction?

• Change in physical state and size

• Change in colour

• Change in temperature

• Change in smell

Explanation

 Chemical reaction can change smell, change in temperature and change in colour with different properties. 

Multiple Choice

10. Sodium : Na :: ? : Potassium

• P

• Pt

• Ca

• K

Explanation

Symbol of sodium metal is Na while symbol of element

potassium is K. 

Multiple Choice

11. Heating of iron and Sulphur to form Iron sulphide

• Periodic change

• Chemical change

• Physical change

• Slow change

Explanation

Heating of iron and sulphur to form Iron sulphate is an example of chemical change because properties of sulphur and iron are totally different from property of iron sulphate.

Multiple Choice

12. For rusting presence of _______________ is essential.

• Air and water

• Low temperature and humidity

• Air and carbon dioxide

• Water and humidity

Explanation

Rusting occurs in presence of air and water. Rusting of iron is a chemical change which do not occurs in absence of air or water

Multiple Choice

13. Normal range of breathing rate per minute in an average adult person at rest is:

• 9-12

• 30-33

• 21-24

• 15-18

Explanation

On an average, an adult human being at rest breathes in and out 15-18 times in a minutes. During heavy exercise, the breathing rate can increase upto 25 times per minute.

Multiple Choice

14. The site of cellular respiration is:

• nucleus

• cell membrane

• chloroplast

• mitochondria

Explanation

Respiration happens inside the cells. A cell organelle called mitochondria is the site of cellular respiration.

Multiple Choice

15. During respiration, breakdown of food takes place

• Between the tissues

• Within the cells

• Outside the cells

• Inside the lungs

Explanation

 Cellular respiration takes place in the cells of all organisms. In the cell, the food (glucose) is broken down into carbon dioxide and water using oxygen. When breakdown of glucose occurs with the use of oxygen it is called aerobic respiration. Food can also be broken down, without using oxygen.

Multiple Choice

16. How many molecules of oxygen are carried by one molecule of haemoglobin?

• 2

• 4

• 6

• 8

Explanation

Each haemoglobin molecule can combine with four oxygen molecules, but with no more. 2 /The complete combination is called oxygen saturation

Multiple Choice

17. More energy is released in

• Fermentation

• Anaerobic respiration

• Aerobic respiration

• Breathing

Explanation

 In an aerobic respiration we use oxygen to break down the food. Due to breaking down of food we get energy stored in it. But due to unavailability of oxygen in an anaerobic respiration, breaking down of food does not take place and we get very less energy. 

Multiple Choice

18. Breathing involves

• Movement of diaphragm and rib cage

• Breaking down of complex food

• Movement of diaphragm and shoulder bone

• Release of energy

Explanation

We take in air through our nostrils, when we inhale air, it passes through our nostril into nasal cavity and from there it reaches our lungs through the wind pipe. Lungs are present in chest cavity which is surrounded by ribs on the sides; diaphragm forms the floor of chest cavity. Breathing involves the movement of diaphragm and the rib cage

Multiple Choice

19. Quantity of haemoglobin is

• Equal in both

• Less in woman

• less in man

• Either more or less

Explanation

Men and women have different mean haemoglobin levels in health in venous blood - women have mean levels approximately 12% lower than men. A normal haemoglobin level for women ranges between 12 to 16 g/dL, whereas it is 14 to 17.4 g/dL for men and 9.5 to 24.5 g/dL for children, depending on their age. 

Multiple Choice

20. Arteries are thick walled because

• They are to pump blood

• The blood flow with jerk

• They are without valves

• They have oxygenated blood

Explanation

Arteries are made of thicker walls because arteries carry oxygenated blood from the heart to different organs. 

Multiple Choice

21. Which of the following is termed as the ‘Grave yard’ of RBC?

• Spleen

• Liver

• Bone marrow

• Kidney

Explanation

The spleen is a centre of activity of the mononuclear phagocyte system and can be considered analogous to a large lymph node, as its absence causes a predisposition to certain infections. Old and damaged RBCs are destroyed in the spleen. Hence, it is known as the graveyard of RBCs.

Multiple Choice

22. Which one of the following process generates a force which pulls water absorbed by the roots?

• Transpiration

• Glycolysis

• Photosynthesis

• Respiration

Explanation

Transpiration pull is referred as suction force and this force is used to draw the water in an upward direction from the roots to the leaves. 

Multiple Choice

23. Sweat contains:

• Water and alkali

• Water and salts

• Water and acid

• Water only

Explanation

Sweat is a liquid that is made by the skin when the body is hot. Sweat is made in sweat glands under the surface of the skin, and it comes out of tiny holes in the skin called pores. Sweat is mostly water, but it also contains some salts. 

Multiple Choice

24. Oxygen carried by blood is released in

• Heart

• Capillaries in body

• Capillaries in lungs

• Arteries

Explanation

The capillaries are thin walled and extremely narrow tubes or blood vessels which connect arteries to veins. The exchange of various materials like oxygen, food, carbon dioxide, etc between the blood and the body cells takes place through capillaries. So oxygen carried by blood is released in capillaries. And the deoxygenated blood coming from the capillaries enters into veins.

Multiple Choice

25. The main function of coloured petals of flowers is to

• To store nectar

• Produce anther

• Attract insects for pollination

• To attract human

Explanation

Petals are modified leaves that surround the reproductive parts of flowers. They are often brightly coloured or unusually shaped to attract pollinators.

Multiple Choice

26. In bread moulds, spores are produced inside

• Ovary

• Sporangium

• Bracts

• Anther

Explanation

 Special spore-bearing organs are present in fungi and algae. These are called sporangiophores. The sporangiophore bears spores. The spores germinate to develop a new plant. So, In bread moulds, spores are produced inside Sporangium

Multiple Choice

27. Yeast is a single celled organism that can multiply in

• Few days

• Few seconds

• Few months

• Few hours

Explanation

 The doubling time for yeast (the time required for a cell to duplicate and divide itself) is about 90 minutes. In contrast, human cells growing in culture need about 24 hours to double.

Multiple Choice

28. Cross pollination help in creating variation as

• Pollen are not carried by wind

• Two different gametes fuse together

• Pollen are heavy

• Pollen get changed during transfer

Explanation

Cross pollination is transfer of Pollen grains to stigma of a flower of another plant of the same species and as in palm. Cross pollination help in creating variation as two different genome fuse together.

Multiple Choice

29. Wind pollinated flowers produce

• Larger sized pollen grains

• Very less number of pollen grains

• Very large number of pollen grains

• Heavy and sticky pollen grains

Explanation

The wind does not deliver pollen directly to any particular plant. Pollinating insects are encouraged to visit the next flower. The wind deposits pollen everywhere at once. Wind pollinated plants therefore have a much greater area to cover, and produce more pollen. 

Multiple Choice

30. A population of genetically identical individuals, obtained from asexual reproduction is

• Clone

• Callus

• Deme

• Aggregate

Explanation

Cloning is the process of producing similar populations of genetically identical individuals that occurs in nature when organisms such as bacteria, insects or plants reproduce asexually. 

Multiple Choice

31. Odometer is used to measure

• Size of the vehicles

• Total time taken

• Total distance travelled

• Speed of the vehicles

Explanation

Odometer is a device, which is used to measure total distance travelled by the vehicle from initial position to final position.

Multiple Choice

32. What is the relation between displacement and speed?

• Displacement = Speed ÷Time

• Displacement = $\frac{1}{speed\ ×\ Time}$

• Displacement = Speed × Time

• Displacement = Time ÷Speed

Explanation

Displacement is referred to as the shortest distance between initial and final positions of a body. Therefore, Displacement = Speed × Time

Multiple Choice

33. A simple pendulum takes 42 s to complete 20 oscillations. What is its time period?

• 4.2 s

• 21 s

• 2.1 s

• 8.40 s

Explanation

Time period is defined as total time taken to complete one oscillation.

Total time = 42 seconds

Number of oscillations =20

1 oscillation = 42/20

Time period = 2.1 seconds

Multiple Choice

34. One hour is equal to

• 3600 seconds

• 1800 seconds

• 1200 seconds

• 600 seconds

Explanation

One hour = 60 minutes (or) 60 x 1 minute but one minute = 60 seconds.

Therefore, one hour= 60 x 60 = 3600 seconds

Multiple Choice

35. Lightning of thunder is heard earlier than it sound because

• Light travels faster than sound

• Speed of light is less in air

• Light is slower than sound

• Sound travels faster in air

Explanation

Lightning of thunder is heard earlier than it sound because light travels faster than sound as Speed of light = 3,00,000 km/h and speed of sound is only 340 m/s. 

Multiple Choice

36. It takes a simple pendulum 28 s to make 16 oscillations .Calculate its time period

• 1.75 s

• 1.5 s

• 2 s

• 3.75 s

Explanation

Time period is the time taken to complete one oscillation. therefore,time period = time taken / no. of oscillations

            =28 s /16 = 1.75 s 

Multiple Choice

37. The time period of a simple pendulum depends upon its:

• Independent of both length of the pendulum and mass of bob

• Both length of the pendulum and mass of bob

• Length of string

• Mass of bob

Explanation

The time period of a simple pendulum does not vary with the mass of the bob or with the distance of the bob from the mean position.

Multiple Choice

38. In a battery, the cells are connected

• Negative to negative terminal

• Any terminal can be connected

• Positive to negative terminal

• Positive to positive terminal

Explanation

 In a battery, the cells are connected positive to negative terminals to complete the circuit. The cells are connected in series with the opposite terminals together. An electric battery is a device consisting of one or more electrochemical cells. When a battery is supplying electric power, its positive terminal is the cathode and negative terminal is anode. 

Multiple Choice

39. ISI mark is issued by

• Standard bureau of India

• Indian standard of bureau

• Indian intelligence bureau

• Bureau of Indian standards

Explanation

 ISI mark is issued by Bureau of Indian standards (BIS) that certifies that instrument is safe and wastage of energy is minimum (energy efficient).The abbreviation of ISI is Indian standard institute, former name of Bureau of Indian Standards. The ISI mark is mandatory for certain products to be sold in India. 

Multiple Choice

40. Where can the key or switch be placed in a circuit?

• Left side of the battery

• Near the positive terminal of the bulb

• Can be placed anywhere in the circuit

• Right side of the battery

Explanation

Switch is a device used to close or open an electric circuit. Switch in a circuit can be place any where.

Multiple Choice

41. In an electric circuit, a key or switch can be placed

• Between bulb and battery

• Between bulb and ammeter

• Any where in the circuit

• Between battery and ammeter

Explanation

In an electric circuit, key or switch can be connected anywhere in the circuit. It is called as a closed circuit.

Multiple Choice

42. Which mark is necessary on electric appliances?

• FICCI

• AGMARK

• ISI

• KSK

Explanation

ISI mark is a certification mark for industrial products in India. The mark certifies that a product conforms to the Indian Standard. The name ISI is an abbreviation of Indian Standards Institute, the former name of the Bureau of Indian Standards. The ISI mark is mandatory for certain products to be sold in India, like many of the electrical appliances like switches, electric motors, wiring cables, heaters, kitchen appliances etc.

Multiple Choice

43. Electricity will not flow through the circuit if

• Circuit is incomplete

• Connector is covered with plastic

• Circuit is complete

• There is a key in the circuit

Explanation

Electric current will not flow through a circuit if the circuit is incomplete. It is to be noted that the resistance of an air gap is infinity. If the circuit is not complete then it is called as open circuit. A closed circuit means a complete electrical connection around which current flows or circulates.

Multiple Choice

44. When a magnetic compass is placed near a current carrying conductor. Compass

• Deflects due to magnetic effect

• Deflects due to heating effect

• Deflects due to chemical effect

• Do not deflect

Explanation

When a magnetic compass is placed near a current carrying conductor, compass deflects due to magnetic effect of electricity. This clearly indicates that compass needle interacts with the magnetic field of the material. 

Multiple Choice

45. In refraction, bending of light rays takes place at the

• End of the second medium

• Boundary of between two media

• Middle of the second medium

• Middle of the first medium

Explanation

The refraction occurs at the boundary of the path of a light wave as it passes from one material into another material crossing the boundary. The tendency of a ray of light to bend one direction or another is dependent upon whether the light wave speeds up or slows down upon crossing the boundary. 

Multiple Choice

46. Lens used in spectacles for correction of defects of vision is

• Always convex

• Concave or convex

• Always concave

• Lens of different shape

Explanation

The convex and concave lenses are used to correct the defective vision. Myopia can be corrected by placing a suitable concave lens in the line of sight. Hypermetropia can be corrected by placing a suitable convex lens in the line of sight. To correct presbyopia, a bifocal lens is used.

Multiple Choice

47. Which of the following instrument do not use lens?

• Spectacles

• Periscope

• Microscope

• Telescope

Explanation

Lens is used in microscope, telescope and spectacles but only mirror is used in periscope. Periscope is based on the principle of successive reflections from two plane mirrors. 

Multiple Choice

48. Rainbow formation takes place due to

• Refraction and dispersion of light

• Reflection and dispersion of light

• Refraction and splitting of light

• Reflection and refraction of light

Explanation

The rainbow is an arch of seven colours visible in the sky which is produced by the dispersion of sun’s light by rainbow drops in the atmosphere. Dispersion of light occurs when white light is separated into its different constituent colours because of refraction and Snell's law. The formation of rainbow is based on the process of dispersion of light and refraction.

Multiple Choice

49. When an object is placed in front of the mirror, the left part appear to be right side the mirror is likely to be

• Plane mirror or convex mirror

• Concave mirror and convex mirror

• Plane mirror or concave mirror

• All of these mirrors

Explanation

Plane mirror or convex mirror shows the phenomenon of lateral inversion to appear left part to right side. So, When an object is placed in front of the mirror, the left part appear to be right side the mirror is likely to be plane mirror or convex mirror. 

Multiple Choice

50. Objects are visible, when reflected light

• Enters to our eyes

• Comes out from the eyes

• Bends towards the normal

• Bounce back from surface

Explanation

We are able to see an object only when light from an object enters our eyes. The light entering our eyes may have been reflected by the object or may have been emitted by the object.