CBSE Class 10 Science Question Paper 2020 Set 2

SCIENCE BOARD EXAM – SET 2

General Instructions:

Read the following instructions very carefully and strictly follow them:

1. This question paper comprises four sections – A, B and C. There are 30 questions in the question paper. All questions are compulsory.

1. Section A: Question numbers 1 to 14 – all questions or part thereof are of one marl each. These questions comprise multiple choice questions(MCQ), Very Short answer(VSA) and Assertion-Reason type question. Answer to these questions should be given in one word or one sentence.

1. Section B: Question numbers 15 to 24 are short answer type questions, carrying 3 marks each. Answer to these questions should not exceed 50 to 60 words.
2. Section C: Question numbers 25 to 30 are long answer type questions, carrying 5 marks each. Answer to these questions should not exceed 80 to 90 words
3. Answer should be brief and to the point. Also the above mentioned word limit be adhered to as far as possible.
4. There is no overall choice in the question paper. However, an internal choice has been provided in some questions in each section. Only one of the choices in such questions have to be attempted.

In addition to this, separate instructions are given with each section and question, wherever necessary.

SECTION - A

<math>14 \times 1 = 14 \text{ MARKS}</math>

1. Which oil should be chaser for cooking to remain healthy?
2. Define the term induced electric current.
3. Answer question numbers 3(a) - 3(d) on the basis of your understanding of the following paragraph and the related concepts.

Around the year 1800, only 30 elements were known Dobereiner in 1817 and Newlands in 1866 tried to arrange the then known elements and framed laws which were rejected by the scientists. Even after the rejection of the proposed laws, many scientists continued to search for a pattern that correlated the properties of elements with their masses.

The main credit for classifying elements goes to Mendeleev for classifying elements goes to Mendeleev for his most important contribution to the early development of a periodic table of elements where in he arranged the elements on the basis of their fundamental property, the atomic mass and also on the similarity of chemical properties. The format of their hydrides and oxides were treated as basic criteria for the classification of the elements. However, Mendeleev's classification also had some limitations as it could not assign the position to isotopes. He also left some gaps in the periodic table.

3(a). State Mendeleev's periodic law.

3(b). Why did Mendeleev leave some gaps in the periodic table?

3(c). If the letter 'R' was used to represent and of the elements in the group, then the hydride and oxide of carbon would respectively be represented as

1. RH4, RO
2. RH₂, RO₂
3. RH₂, RO
4. RH₄, RO₂

3(d). Isotopes are

1. Atoms of elements with similar chemical properties but different atomic masses.
2. Atoms of different elements with similar chemical properties but different atomic masses.

1. Atoms of elements with different chemical properties but same atomic masses.
2. Atoms of different elements with different chemical properties but same atomic masses.

1. Answer question numbers 4(a) - 4(d) on the basis of your understanding of the following paragraph and the related studied concepts:

India today is facing the problem of overuse of resources, contamination of water and soil and luck of methods of processing the waste. The time has come for the world to say goodbye to "single-use plastics". Steps must be undertaken to develop environment -friendly substitutes, effective plastic waste collection and methods of its disposal.

Indore treated 15 lakh metric tonnes of waste in just 3 years, through biomining and bioremediation techniques. Bioremediation involves introducing microbes into a landfill to naturally 'break' it down and biomining involves using trommel machines to sift through the waste to separate the 'soil' and the waste component. The city managed to chip away 15 lakh metric tonnes of waste at a cost of around Rs 10 crore. A similar experiment was successfully carried out in Ahmedabad also.

4(a) State tow methods of effective plastic waste collection in your school.

4(b) Name any two uses of "single-use plastic" in daily life.

4(c) If we discontinue the use of plastic, how can an environment-friendly substitute be provided?

4(d) Do you think microbes will work similarly in landfill sites as they work in the laboratory? Justify your answer.

1. Fertilization is the process of
2. Transfer of male gamete to female gamete
3. Fusion of nuclei of male and female gamete.
4. Adhesion of male and female reproductive organs
5. The formation of gametes by a reproductive organ

1. In the excretory system of human beings, some substances in the initial filtrate such as glucose, amino acids, salts and water are selectively reabsorbed in
2. Urethra (b) Nephron (d) Urinary bladder

(OR)

Pseudopodia are

1. Small hair-like structures present on unicellular organisms
2. False feet developed in some unicellular organisms
3. Long, tube-like structures coming out of the mouth
4. Suckers which are attached to the walls of the intestines