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CBSE Sample Papers for Class 10 Science SA2 | Download PDF With Solutions


CBSE Sample Papers for Class 10 Science SA2

CBSE Sample Papers for Class 10 Science SA2: Candidates who are looking for CBSE Sample Papers for Class 10 Science SA2 they can download it from here in PDF Form along with solutions. Below given previous year CBSE Sample Papers will help you to know the idea of questions asking in Central Board of Secondary Education Board Exam.

All the candidates are advised to practice all the three sections of Science such as Physics, Chemistry and Biology. After revising all the chapters of science, you need to solve out below stated CBSE Sample Papers for Class 10 Science to get a short idea about format of question as well as marking scheme.

To get entire CBSE Sample Papers for Class 10 Science SA2, you need to scroll down the page which is well prepared by the unit of www.privatejobshub.in

CBSE Sample Papers for Class 10 Science SA2

CBSE Previous Year Questions and Answers of Science:

Question 1: You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?

Answer: The contents of each test tube would be identified by change in colour of red litmus paper. For example, when we wet the red litmus paper with the basic solution, it changes into blue colour. Put the changed blue litmus paper in the solution which turns the blue to red will be the acidic solution. The solution, which has no effect on any litmus paper, will be neutral and hence it will be distilled water.

Question 2: Why should curd and sour substances not be kept in brass and copper vessels?

Answer: Curd and other sour foodstuffs contain acids, which can react with the metal of the vessel to form poisonous metal compounds which can cause food poisoning and damage our health.

Question 3: Which gas is usually liberated when an acid reacts with a metal?

Answer: When an acid reacts with metal, a salt and hydrogen gas is formed. i.e NCERT-Solutions-Acids-Bases-and-Salt-CBSE-Class-10-Science-Q3

Download Updated: CBSE Class 10 Syllabus

Question 4: Metal compound A reacts with dilute hydrochloric acid to produce effervescence. The gas evolved extinguishes a burning candle. Write a balanced chemical equation for the reaction if one of the compounds formed is calcium chloride.

Answer: The gas that extinguishes a burning candle is carbon dioxide, which is formed by the action of dilute hydrochloric acid on a metal carbonate and produces effervescence. Now, since one of the compounds formed is calcium chloride, it shows that the metal compound is calcium carbonate. Thus, the metal compound A is calcium carbonate (CaCO3). Calcium carbonate reacts with dilute hydrochloric acid to form calcium chloride, carbon dioxide and water. This can be written as:

Question 5: Why do HCl, HNO3, etc., show acidic characters in aqueous solutions while solutions of compounds like alcohol and glucose do not show acidic character?

Answer: An acid is a substance, which dissociates on dissolving in water to produce hydrogen ions [H+(aq) ions]. The acids like HCl, H2SO4, HNO3 and CH3COOH, etc., show acidic character because they dissociate in aqueous solutions to produce hydrogen ions, H+(aq) ions.

The compounds such as glucose and alcohol also contain hydrogen but they do not show acidic character. The aqueous solutions of glucose and alcohol do not show acidic character because the hydrogen in them does not separate out as hydrogen ions [H+ (aq) ions] on dissolving in water.

Get Here Newest and Latest: CBSE Exam Pattern

Question 6: Why does an aqueous solution of acid conduct electricity?

Answer: The aqueous solution of an acid conducts electricity due to the presence of charged particles called ions in it.

Question 7: Why does dry HCl gas not change the colour of the dry litmus paper?

Answer: Dry HCl gas does not contain any hydrogen ions in it, so it does not show acidic behaviour. In fact, dry HCl gas does not change the colour of dry litmus paper as it has no hydrogen ions [H+(aq) ions] in it.

Question 8: While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?

  • Diluting an acid should be done by adding concentrated acid to water gradually with stirring and not by adding water to concentrated acid.
  • The heat is evolved gradually when a concentrated acid is added to water for diluting an acid and the large amount of water is easily absorbed.
  • If, however, water is added to concentrated acid to dilute it, a large amount of heat is evolved at once. The heat generated may cause the mixture to splash the acid on our face or clothes and cause acid burns.

Question 9: How is the concentration of hydronium ions (H3O+) affected when a solution of an acid is diluted?

Answer: When the concentrated solution of an acid is diluted by mixing water, the concentration of hydronium ions H3O+ per unit volume decreases.

Question10: How is the concentration of hydroxide ions (OH-) affected when excess base is dissolved in water?

Answer: When the solution of a base is diluted by mixing more water in it, the concentration of hydroxide ions (OH– ions) per unit volume decreases.

Question 11: Give any two ways in which biodegradable substances would affect the environment.

Answer: They may produce foul smell during decomposition process. They may produce some harmful gases such as ammonia, methane, carbon dioxide, etc., which can further-cause global warming

Question 12: Which groups contain only biodegradable items?

Answer:  Fruit-peels, cake and lime-juice and Cake, wood and grass

Question 13: What is the role of decomposers in the ecosystem?

Answer: Role of decomposers in the ecosystem:
  • They help in breaking down the complex organic into simple inorganic that go into the soil and are used up by the plants.
  • They the nutrient pool of the putting In this way, ad as cleansing agents of nature.
  • They help in maintaining the fertility of by adding humus content to it.
Question 14: What will happen if we kill all the organisms in one trophic level?

Answer: If we kill all the organisms in one trophic level, then transfer of energy as well as matter to next higher level will stop. It will lead to over- population at one particular level causing amongst the individuals. This would seriously disturb the food chain and can cause the collapse of an ecosystem even.

Question 15: Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem?

Answer: Yes, the impact Of removing all the Organisms in a trophic level will be different for different trophic levels. It will not be possible to remove any organism in any trophic level without causing damage to the ecosystem.

Question 16: What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?

Answer: The accumulation of harmful chemicals in the body of living organisms at different tropic levels in a food chain is called biological magnification. Yes, the concentration of these harmful chemicals will be different at different tropic levels. It will be maximum at the last tropic levels which are mostly of the top carnivores (quaternary consumers).

Question 17: What are the problems caused by the non-biodegradable wastes that we generate?

  • Non-biodegradable wastes persist in the environment for a long time and cause greater harm to the various members of the ecosystem by causing biological magnification.
  • Non-biodegradable waste such as fertilizers, pesticides, weedicides, etc., changes the soil chemistry. in turn affects the fertility of soil and subsequently reduces the crop yield.

Question 18: If all the waste we generate is biodegradable, will this have no impact on the environment?

Answer: Biodegradable waste will be recycled easily by the decomposers such as bacteria and fungi. It will have only this bad impact on our environment that, many Of the gases released during decomposition process may result in global warming.

Question 19: Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?

Answer: The ozone shields the surface of the earth from ultraviolet (UV) radiation from the sun. These radiations are highly damaging as they can cause cancer in both plants and animals, damage to eyes and immune system. They can also lead to variations in global rainfall, ecological disturbances and dwindling of global food supplies

Question 20: What are the different ways in which individuals with a particular trait may increase in a population?

Answer: Different ways are:
  • Variation
  • Natural selection
  • Genetic drift (isolation)
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CBSE Sample Papers for Class 10 Science SA2 (Objective Questions):

Question 1:  A chemical reaction involves in

a.    Only breaking of bonds
b.    Only formation of bonds
c.    Both breaking and formation of bonds
d.    None of these

Answer: (c) 

Question 2: A balanced chemical equation always obeys

a.    Law of conservation of mass
b.    Law of thermal equilibrium
c.    Law of conservation of energy
d.    All of the above

Answer: (a)

Download Here: CBSE 10th Time Table

Question 3: Single displacement reaction involves:

a.    Oxidation
b.    Reduction
c.    Redox
d.    Heating

Answer: (c)

Question 4: String of ants, bees contain

a.    Formic acid
b.    Vinegar
c.    Succinic acid
d.    Common Salt (NaCl)

Answer: (a)

Question 5: Some stale food gives a bad taste and a bad smell because of:

a.    Corrosion
b.    Displacement
c.    Heating
d.    Rancidity

Answer: (d)

Question 6: A red brown gas is released on heating lead nitrate. It is an example of

a.    Combination reaction
b.    Oxidation reaction
c.    Decomposition reaction
d.    Reduction reaction

Answer:  (c)

Prepare Well From: NCERT Books For Class 10

Question 7: The sign indicates
a.    release of gas
b.    dissolution of gas
c.    formation of a precipitate
d.    lowering of temperature

Answer: (c)

Question 8: Why do gold and silver do not corrode?

Answer: It is because they are less reactive.

Question 9: What do you mean by balanced chemical equation?

Answer: An equation that has equal number of atoms of each element on both the sides of equation is called balanced chemical equation, i.e., mass of the reactants is equal to mass of the products.

                    e.g., 2Mg + O2 2MgO

Question 10: Define rancidity.

Answer: When fats and oils are oxidized, they become rancid and their smell and taste change. This process is known as rancidity

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