CBSE Class 3 Science ISO Olympiad MCQs with Answers Set D

1. Water droplets that are too heavy to float make
(a) fog
(b) clouds
(c) rain
(d) smoke
Answer : (c) Very tiny and light droplets of water float in the air (forming clouds). Water droplets that are too heavy to float make rain.

2. Which of the following does not take the shape of the container it is in ?
(a) Pencil
(b) Oil
(c) Water
(d) Milk
Answer : (a) Liquid is having a property of taking the shape of the container it is in. Oil, water and milk are liquid they will take the shape of the container they are poured in. Pencil is solid and solids have a definite shape.

3. Which of the following will not dissolve in water?
(a) Salt
(b) Sugar
(c) Sand
(d) Baking soda
Answer : (c) Sand is insoluble, it does not dissolve in water. It settles down in the water protects the brain and supports the other soft tissues of the head.

4. I protect the brain. I consist of bones which are fused firmly together to form a shell like structure. What am I?
(a) Skull
(b) Ribcage
(c) Spine
(d) Sternum
Answer : (a) The skull is a bony structure, the head in the skeleton. It

5. The bird that lays its eggs in the nest of a crow is
(a) cuckoo
(b) parrot
(c) wood pecker
(d) pigeon
Answer : (a) Cuckoo lays its eggs in the nest of other birds.

6. Soil helps trees because soil
(a) makes food for the trees
(b) moves the tree seeds to new places
(c) gives nutrients to the trees
(d) turns the roots into new trees
Answer : (c) An important function of soil is to store and supply nutrients to the plants or trees. This ability of soil is known as soil fertility.

7. The upper part of an umbrella is made of a special type of cloth. Which of the following BEST describes an umbrella cloth?
(a) It must be very heavy.
(b) It must not be white in color.
(c) It must be able to sink in water.
(d) It must not allow liquids to pass through.
Answer : (d) Umbrella cloth must not allow liquids to pass through.

8. _______are known as food factories of a plant.
(a) Green leaves
(b) Roots
(c) Stem
(d) Flower
Answer : (a) A green substance in plants called chlorophyll traps the energy from the sun needed to make food. Chlorophyll is mostly found in leaves. So green leaves are known as food factories of a plant.

9. Weather is caused by the
(a) sun
(b) night air
(c) temperature
(d) clouds
Answer : (a) The sun provides the energy that causes earth’s weather.

10. The thick layer of __________ under the bear's skin keeps them warm and allows them to go for weeks without eating if necessary.
(a) Fat
(b) Blood
(c) Hair
(d) Skin
Answer : (a) Fat layer under bear skin keeps them warm

11. What would you have to add to solid ice to make it turn it into a liquid?
(a) Liquid
(b) Heat
(c) Blender
(d) More solid
Answer : (b) Heat

12. In which Earth layer do most grasses grow?
(a) Solid rock
(b) Subsoil
(c) Topsoil
(d) Bedrock
Answer : (c) In earth, the grasses grow on the top layer as it makes easier for the grass seed to take root.

13. Which of these do people build to stop flooding?
(a) Sidewalks
(b) Dams
(c) Bridges
(d) Streets
Answer : (b) Dams are build by people to stop flooding.

14. You decide to help your family cook breakfast one weekend. Which of the following actions would be considered a chemical change?
(a) Cutting up the vegetables
(b) Slicing an orange
(c) Making scrambled eggs
(d) Folding the napkins
Answer : (c) Making scrambled eggs

15. Which is the longest bone of the human body?
(a) Stapes
(b) Skull
(c) Ribs
(d) Femur
Answer : (d) Femur is the longest and strongest bone of the human body, extending from the hip to the knee.

16. Which of the following plants will not be able to survive?

(a) (A) & (B)
(b) (B) & (C)
(c) (C) & (D)
(d) (A), (B) & (C)
Answer : (d) Plant A, B and C will not survive: Any plant without root and leaves can not survive.
Root provides nutrients to the plant and leaves store food for the plants.

17. Trunk is the main stem of the tree.
It divides into many branches higher up in tree. The ________ of the tree protects the trunk
(a) stem
(b) bark
(c) pigment
(d) roots
Answer : (b) Bark of the tree protects the trunk. It’s an outer protective layer that makes the trunk, branches and roots grow thicker overtime.

18. In desert plants, leaves modify into thorns. How do thorns help a plant?
(a) They catch food
(b) They store water
(c) They protect the plant from being eaten by animals
(d) They make the plant attract bees
Answer : (c) Desert plants like cactus has leaves modified into thorns.
These thorns protect the plant from being eaten by animals.

19. Which of the following animals can change body colouring to protect themselves from their enemies?

Answer : (b) The animal shown in the picture is chameleon, it changes its skin colour to protect itself from its enemies.

20. Look at the poster below.

Based on the given informatìons whìch of the following statements is true about the lost animal?
(a) It is a carnivore
(b) It gives birth to young ones
(c) It lives only on land
(d) It lays one egg at a time
Answer : (a) Based on the given information it’s true that the lost animal is a carnivore as it feeds on insects only.

21. Water boils at ________ and freezes at ________
(a) 10°C 100°C
(b) 100°C, 0°C
(c) 36.7°C, 0°C
(d) 100°C, 26°C
Answer : (b) Water boils at 100°C and freezes at 0°C.

22. Mr. Verma reuses water which was used to wash vegetables, to water his plants. He is practicing --------- of water
(a) pollution
(b) conservation
(c) evaporation
(d) desalination
Answer : (b) Conservation of water means, protecting water from pollution and being wasted. Water used for washing vegetables can be used for watering plants. This conserves some water.

23. Which part of the given figure, are you supposed to consume?

(a) Root
(b) Leaf
(c) Stem
(d) Fruit
Answer : (a) The given figure shows a raddish. It is an edible root vegetable.

24. Food with lots of sugar and starch are rich in
(a) fats
(b) proteins
(c) carbohydrates
(d) vitamins
Answer : (c) Food with lots of sugar and starch are rich in carbodydrates. Carbohydrates are neutral compounds of carbon, hydrogen and oxygen.
Carbohydrates in simple form such as sugars and in complex form such as starch and fibre.

25. Which of the following activities should be done in a house?
(a) We should keep our house clean
(b) We should sweep the floor of all the rooms
(c) Floor should be mopped with phenyl everyday
(d) All of the above
Answer : (d) We should keep our house clean, sweep the floor of all the room and should be mopped with phenyl everyday.

26. You will find me selling medicines in a medicine shop.
I am a ——
(a) chemist
(b) doctor
(c) nurse
(d) surgeon
Answer : (a) A chemist sells medicines in a medicine shop. Doctor and surgeon treats patients. Nurse takes care of the patients

27. In a type of script, row of raised dots are made on a thick paper, which can be read by running the fingers on them. This type of script is known as ——.
(a) Louis script
(b) Marconi script
(c) Braille script
(d) Wright script
Answer : (c) Braille script, a system of raised dots made on a thick paper, which can be read by running the fingers on them. It is used by the blind people.

28. Which of the following telephone services can be used within the country?
(a) PCO
(b) STD
(c) ISD
(d) Both (a) & (b)
Answer : (d) PCO (Public call Office) service is used for the local calls, this facility is located at public places within a country.
STD (Subscriber Trunk Dialling) service is used for local and long distance calls within the country. ISD (International Subscriber Dialling) service is used for international calls world wide (outside the country)

29. Select the odd one out from the following

Answer : (a) Tractor is odd one out in the sense that it is used in agriculture by farmers.
Car, bus and autorickshaw are used to travel from one place to another by anyone in the city.

30. Your baby sister is sleeping in your room. You are reading a book at your study table. Your baby sister wakes up and lets out a cry. Which of your senses help you to know that your baby sister is crying?
(a) Sense of touch and sight
(b) Sense of smell and touch
(c) Sense of hearing and touch
(d) Sense of sight and hearing
Answer : (d) Sense of sight helps in seeing that baby sister wakes up and sense of hearing helps in hearing the sound of her cry

31. Which of the following is WRONGLY classified?
(a) Digestive system -- Stomach Skeletal system --- Skull
(b) Digestive system --- Mouth Skeletal system ---- Ribcage
(c) Digestive system --- Large intestine Skeletal system ---- Spine
(d) Digestive system ---- Nostril Skeletal system ------Heart
Answer : (d) Nostril is part of respiration system. Heart is part of circulatory system.

32. Digestion starts here and food begins its journey through the digestive system.Here food is chopped and chewed into smaller pieces. Which part of the digestive system is being described above?
(a) Teeth
(b) Intestine
(c) Stomach
(d) Mouth
Answer : (d) Digestion starts when you put food in your mouth where food is chopped and chewed into smaller pieces by your teeth for easy digestion of food.

33. Why is Sun important to the Earth?
(i) It provides green plants with light energy to make food.
(ii) It provides heat to enable living things to survive on Earth.
(iìi) It rotates around the earth to give us seasons
(a) (i) & (ii)
(b) (i) & (iii)
(c) (ii) & (iii)
(d) (i), (ii) & (iii)
Answer : (a) Sun is the source of energy. It provides heat to enable living things to survive on earth and provides light energy which is used by green plants to make their food.

34. You are making a model of the Earth and Moon to show their relative sizes and massiveness. If you take cricket ball as an Earth, then _________ can be taken as moon
(a) Lawn tennis ball
(b) Table tennis ball
(c) Basket ball
(d) Volley ball
Answer : (b) The moon has a diameter of 3476 kilometers and is about one fourth of the size of earth.

35.

The best material to make the ball with is
(a) Cotton
(b) Plastic
(c) Rubber
(d) Metal
Answer : (c) A ball is supposed to bounce.
Good material for making a ball is rubber.

36. Which of the following is made of one material only?

(a) (A) & (B)
(b) (A), (B) & (D)
(c) (B) & (C)
(d) (C) & (D)
Answer : (c) Newspaper is made up of paper only and muffler is made up of wool only. Specs is made up of plastic and glass. Pen is made up of plastic and metal like steel.

37. Which of the following revolves(s) around the Sun ?

(a) (A) & (E)
(b) (A), (B) & (C)
(c) (A), (B), (D) & (E)
(d) (A), (B), (C) & (E)
Answer : (a) ‘A’ represents earth, it’s a planet and revolves around the sun. Stars, cloud and moon do not revolve around the sun. ‘E’ represents another planet. All 8 planets revolve around the sun.

38. I revolve around the Sun. I am first member of the solar system. I am the hottest of all other members.
What am I?
(a) Earth
(b) Mercury
(c) Mars
(d) Jupiter
Answer : (b) Solar system consists of a sun and 8 planets in the order Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Mercury is closest to the sun therefore the hottest of all other members.

39. In which of the following situations given below is the sense of smell, taste, touch and sight used at the same time?
(a) A blind person moving around
(b) A girl using the telephone
(c) A man doing repair works for his bicycle
(d) A woman making and baking cookies
Answer : (d) A woman making and baking cookies uses her sense of smell, taste, touch and sight at the same time.

40. Look at the animals below and select one that don`t belong to the group

Answer : (c) A frog is an amphibian and can live on land and in water. All other are insects and live on land.