Question

1) Wood, coal, petrol or cooking gas are burnt for getting energy in presence of oxygen. The common substance that burns in all these fuels is 'Carbon'. During the ____ process carbon combine with oxygen in air and the product ______ is formed.

a) Dehydration, CO2

b) Combustion, CO2

c) RespiratIon, CO2

d) Photosynthesis, CO2

2) To soften the hard water, a solution of washing soda is added to it. This results in a chemical reaction to form a precipitate of insoluble carbonate salts of calcium and magnesium. Complete the reaction: CaCl2 + ____ ---> CaCO3 + _____

a) NaOH, H2O

b) NaCl, Na2CO3

c) Na2CO3, NaCl

d) Na2CO3, H2O

3) The chemical bond formed due to an electrostatic force of attraction between the oppositely charged cation and anion is called an ionic bond or an electrovalent bond. One ionic bond is formed due to the electrical charge _____ on an ion.

a) +2, -1

b) +1, -2

c) +2, -2

d) +1, -1

4) Acids are soluble in water and they are corrosive in nature. Acids present in food stuffs are called natural acids or carbonic acids. Main constituent of acid is ____.

a) Hydrogen ion

b) Hydronium ion

c) Hydroxide ion

d) Hydride
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Answer 1

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1). Fuels burns in the presence of oxygen during the process of combustion and carbon combine with oxygen in air and the product is carbon dioxide.

So, ur answer is option b) combustion, co2.

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Answer 2 :-

ur answer is option c.

cacl2 + Na2co3 ———› caco3 + 2NaCl

sodium carbonate (Na2co3) is used for softening hard water.

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Answer 3 :-

Ur answer is option d)

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Answer 4 :-

Main constituents of acids are hydronium ions (H3O) ions .

So ,ur answer is option b.