CBSE Class 10 Science 2018 Important Topics, Solved Answers And Model Question Papers

Chemical Reactions

Question

Name the reducing agent in the following reaction:

3 MnO2 + 4AI ----> 3Mn + 2Al2O3

Which is more reactive - Mn or Al and why?

Solution

Al is the reducing agent because Al is more reactive than Mn because Aluminium displaces Manganese from its oxide.

Acids Bases and Salts

Question

What is the acid present in the following food?

1) Tomato 2) Vinegar 3) Tamarind

Answer

1) Tomato - Oxalic acid
2) Vinegar - Acetic acid
3)Tamarind - Tartaric acid

Metals And Non-Metals

Question

Justify the following statements

1. School bells are made up of metals.
2. Electric wires are made of copper.

Answer

1. Metals are sonorous in nature. They produce sound when struck with a hard substance. That is why school bells are made up of metals.
2. Copper is a good conductor of electricity. So electric wires are made of copper.

Carbon And Its Compounds

Question

Name the functional groups

1. -OH 2. -COOH

Answer

1. Alcohol group 2. Carboxylic acid group

Periodic Classification of Elements

Question

Chlorine, bromine and iodine form a Dobereiner's triad. The atomic masses of chlorine and iodine are 35.5 and 126.9 respectively. Predict the atomic masses of bromine.

Answer

Atomic mass of Br = [35.5 + 126.9]/2
= 162.4/2
= 81.2

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CBSE Class 10 Science Papers

In order to find the previous years question papers and solved answer papers, check out the links below:

• CBSE Class 10 Science Model Annual Answer Paper 2017
• CBSE Class 10 Science Sample Question Paper 2017-2018
• CBSE Science previous years question papers and sample papers complete list