CLASS 10 SCIENCE Short and Very short Answers

Class 10 Students can go through this as a ready reckoner for their Science Board Examination 

All answers are given in blue

1. What happens when Silver chloride is put under sunlight?

Silver metal and chlorine gas are formed.

2. Acid used in refining of petroleum to remove sulphur and other compounds

Sulphuric acid

3. The magnetic field lines de to straight wire carrying a current are ___

Circular: Concentric circles with centre at the axis of the conductor.

4. When more than one resistors are in series, the quantity that remains same in them is ________

Current:  Resistors in series have same current

5. The percentage of solar radiation absorbed by all the green plants for the process of photosynthesis is about _________

1 percent : The green plants convert this into food energy and make this energy available to the rest of the ecosystem.

6. The property of a proton that can change while it moves freely in a magnetic field

Momentum

When a proton moves in a magnetic field, its velocity changes. Momentum = mass x velocity

As velocity changes, momentum also changes

7. The branch of biology related with heredity and variation is ___________

Genetics

8. In the slide of an epidermal peel, the parts which appear pink after staining with safranin are ___________

All parts in the peel

Safranin stains epidermal cells of the onion peel

9. The property of a metal by which it can be drawn into a wire is _________

Ductility

10. The two versions  of a trait which are brought in by the male and female gametes are situated on __________

Copies of the same chromosome.

Each parent contributes one copy of the gene for a particular trait

11. The magnetic field strength of a solenoid can be increased by inserting _________

An iron piece into it 

12. Mendel selected garden peas as his experimental material because

Pea plants possess a number of well defined contrasting characters, have a short life cycle and produce many seeds in one generation.

13. Organisms that reproduce by the asexual method are _______

Amoeba - binary fission

Yeast - budding

Banana - vegetative propagation from the stem.

14. Accumulation of non biodegradable pesticides in the food chains in increasing amount at each higher trophic level is ___________

Biological magnification

15. The most likely temperature of the filament of an electric light bulb when it is working on the normal 220 V supply line _______

2500°C

16. The energy rich compound produced through respiration is _______

ATP

17. _______ is a product of  meiosis

Megaspore

It is a haploid cell formed by meiosis in the megaspore mother.  It is the first cell of female gametophyte

18. ______ is the father of genetics

Gregor Mendel

 19. Part of the alimentary canal where food is fully digested 

Small intestine

20. Rule determines the flow of current in a conductor

Flemings right hand rule

21. Chemically rust is ____________

Hydrated ferric oxide

Rust is an iron oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture.  Fe₂O₃.H₂O  

22. Bleaching powder is produced by the action of chlorine on _______

Dry slaked lime

Ca(OH)₂ + Cl₂ ---> CaOCl₂ + H₂O

23. As compared to daytime, the amount of carbon dioxide released by the plants during night time is more because ____________

Major amount of carbon dioxide produced is used up for photosynthesis during daytime.

24. In human males, all the chromosomes are perfectly paired except one. The unpaired chromosome is __________

In human males, all the chromosomes (22 Autosomes) are paired perfectly except the 23rd chromosome.  The unpaired chromosomes are X and Y

25. A coil of many circular turn wrapped around an insulator forms a ___________

Solenoid

26. Two LED bulbs of 10 W and 5 W are connected in series.. If the current flowing through 5 W bulb is 0.005 A, the current flowing through 10 W is ___________

0.005 A

Current in a circuit made up of series of resistors is the same throughout.

27. How much of the net primary productivity of a terrestrial ecosystem is eaten and digested by herbivores?

10 percent

28. Exposure to UV radiation causes eye disease like 

Cataract

Cataract is a clouding of the lens in the eye which leads to a decrease in vision

29. Compound that contains carboxylic group 

CH₃CH₂COOH

30. Compound that contains alcoholic group

CH₃CH₂OH

31. Compound that contains an ester group

CH₃COOC₂H₅

32. Number of electrons in the outermost shell of the atom of a non-metal 

5, 6 or 7

33. Esters which contain 10 Hydrogen atoms per molecule

Ethyl propanoate and Methyl butanoate

34. Inner lining of stomach is protected by _____________  from HCL acid

Mucus: A layer of mucus along the inner walls of the stomach protects the cell linings of the organ from HCL acid.

35. Offspring formed as a result of sexual reproduction exhibit more variations because 

genetic material comes from two parents of the same species.

36. For evolution to occur in a population __________ must happen

The frequencies of some alleles in a population's gene pool must change over successive generations.

37. The kidneys in human beings are a part of the system for ___________

Excretion: The process by which metabolic wastes and other non useful materials are eleminated from an organism. In humans, kidneys filter waste products from the blood.

38. An electric bulb is rated 220 V and 100 W.  When it is operated on 110 V, the power consumed will be ___________

25 W

P= V² / R

39. Ozone depletion has resulted in ________

More UV radiations on earth.

40. Chemical equation that represents combustion of methane to produce heat energy

CH₄ + 2O₂   ----> CO₂  + 2H₂O

41. Increasing order of acidic strength

Water, Acetic acid, Hydrochloric acid

Distilled water is neutral

Acetic acid is an organic acid

HCL is an organic acid

42. A pair of natural indicators

Turmeric and Litmus

Turmeric changes colour from yellow to reddish brown in basic solutions and litmus changes colour from blue to red in acidic solutions. This is a natural way to test the pH

43. A chemical compound used in glass, soap and paper industries is _____________

Washing soda also known as sodium carbonate

44. A plant hormone that promotes cell division

Auxins 

They are produced in the apices of the stem and root and help in their elongation.  

45. Part of a flower that attracts insects for pollination

Petals

These are the coloured parts of the flower

46. The phenomena of light involved in the formation of a rainbow in the sky are 

Refraction, Dispersion and Total internal reflection

47. A food chain will be more advantageous in terms of energy if it has ___________

2 trophic levels

A food chain with 2 trophic levels - producer and primary consumer has least energy loss

48. Auxins are synthesized in ________

Young tip of roots and shoots

49. Two pairs of visible contrasting characters of garden pea plants used by Mendel

Height of the plant (Tall and dwarf)

Colour of the flower (violet and white)

50. In humans, the probability of getting a male or a female child is 50%. Explain

If a Y bearing sperm fertilizes the egg, the zygote will be a male (XY) and when X bearing sperm fertilizes the egg, the zygote will be a female (XX). The ratio of X and Y chromosomes in a male gamete is 50:50

51. Two causes of hypermetropia 

Focal length of the eye lens is too long

Eyeball has become too small

52. Type of lens used to correct hypermetropia

Convex lens

53. Decomposers: Creatures that break down dead or decaying species. 

54. Juice of tamarind turns blue litmus to red. This is due to the presence of ___________

Tartaric acid

55. An example of a combination reaction

Burning of coal

Coal (carbon) burns in air to produce carbon dioxide and heat energy.

56. Name the oxide that can react with HCl and KOH to give corresponding salt and water

Al₂O₃  This is an amphoteric oxide 

57. A gland that does not occur in pairs 

Pituitary gland

58. In human respiratory system, when a person breathes in, the position of ribs and diaphragm will be _________-

Lifted ribs and flattened diaphragm

59. Where is bile juice stored in human body?

Bile is a fluid that is made and released by the liver and stored in the gallbladder.

60. Uses of bile juice

It helps with digestion.

Breaks down fats into fatty acids which are taken into the body by the digestive tract  

61. Part of the eye that plays a major role in the process of accommodation

Ciliary muscles

These muscles change the focal length of the eye lens depending on the position of the object.

62. Part of the brain responsible

Cerebrum

63. Part of the brain that controls hunger

Hypothalamus

64. Two properties of heating elements

High melting point

High resistivity

64. Glands present in buccal activity

Salivary glands

65. Name the two organs have a sphincter muscle at their exit.

Esophageal and Pyloric sphincter

66. A piece of zinc metal gets reddish brown coating when kept in copper sulphate solution for some time. Why?

This occurs due to the displacement reaction where zinc reacts with copper ions in the solution to form metallic copper on the surface of zinc

67. Copper is more reactive metal than zinc. True or false?  Explain

This is false.  Zinc is more reactive than copper.  The reactivity series of metals places zinc higher than copper which indicates that zinc can displace copper from its compound in solution.

68. Red coloured light is scattered the most so as to be visible from a large distance. True or false? Explain

This is false. Red colour has a longer wavelength and hence scattered the least.

69. Role of pepsin in the digestion of food

Helps to digest proteins in stomach

70. Role of trypsin in the digestion of food

Breaks down proteins into amino acids and peptides

71. Role of lipase in the digestion of food

Breaks down emulsified fats into fatty acids and glycerol

72. Role of salivary amylase

Breaks down starch into sugar

73. An example of an endothermic reaction

Cooking of food

74. Electronic configuration of three elements X - 2,8,7 , Y - 2,8,2. Classify as metals or non-metals

X is a non-metal and Y is a metal

75. When 50 g lead powder is added to 300 ml of blue copper sulphate solution, after a few hours, the solution becomes colourless. Name the type of reaction.

Displacement reaction

76. Oxides of aluminium and zinc are _____

Amphoteric 

77. A metal and a non-metal that exists in liquid state at room temperature are respectively 

mercury (metal) and bromine (non-metal).

78. The compound having maximum number of water of crystallization in its crystalline form in one molecule is 

Hydrated sodium carbonate.

79. Name and formula of third member of homologous series of alkyne

Butyne C₄H₆

80. A stomata closes when there is 

no sunlight.

GIVE REASONS

1. Zinc oxide is an amphoteric oxide

It is because it reacts with both acids and alkalis to give salt and water.

2. Sodium metal is stored in bottle filled with kerosene oil

It is a very reactive metal. If it comes in contact with the moisture present in air, sodium hydroxide will be formed which is a highly exothermic reaction.

3. In the reactions of nitric acid with metals, generally hydrogen gas is not evolved.

As nitric acid is a strong oxidising agent, it oxidizes hydrogen to produce water.

4. Certain metals are used for making cooking utensils

Metals like aluminium and copper are used for making cooking utensils as they are good conductors of heat and have high melting points.

5. Farmers treat soil with quicklime when tilling

To change the nature of soil to neutral or basic

6. Ancient scriptures and marble structures are conserved by treating them with certain chemicals

To protect them from effects of certain gases present in environment and acid rain.

7. Bee sting is treated with baking soda paste whereas wasp sting is treated with dilute vinegar.

Bee sting is acidic and wasp sting is basic

8. Alveoli in lungs are richly supplied with blood capillaries

The exchange of gases takes place between the membrane of alveoli and the surrounding capillaries.  The blood capillaries covering the alveoli have low oxygen and high carbon dioxide concentration.  This allows oxygen to diffuse into the blood and carbon dioxide out of the blood.

9. Respiratory pigment in the blood takes up oxygen and not carbon dioxide

The respiratory pigment haemoglobin has high affinity for oxygen and so it transports oxygen into the body. Carbon dioxide is more soluble in water and hence transported in dissolved form in the blood.

Note: Students, kindly refer your textbook in case of any doubt or clarification as regards to the questions and answers given above.