Humans are protected from some infection by specialized cells which produce chemicals that

Answer: Option (C)

Explanation: Hydrogen and Helium initially, both were present on the earth's atmosphere. But later they were reduced upto a huge extent. Due to the location of earth near to the sun, these gases must have evaporated from the earth's atmosphere. At present the amount of hydrogen and helium is very less.

Thus, the correct answer is option (C).

The correct option is C.

When writing chemical equations, the chemical symbols of the element are usually used together with numbers to indicate the ratio of each element in the chemical compounds. The additional sign is usually used in between the reactants and the products. The arrow sign in used to show the direction in which the reaction is proceeding. In the correct option given above, the arrow sign is used to indicate that the reaction is moving in the forward direction.

Answer:

C) C+ O -> CO2

Explanation:

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