Consider the equation: ca+o2→cao what needs to be done in order to balance the equation? a place a 2 in front of the o2 and the cao . b place a 2 in front of the cao only. c place a 2 only in front of the ca . d place a 2 in front of the ca and the cao .

D

Explanation:

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Answer : The correct option is, (D) Place a 2 in front of the Ca and the CaO.

Explanation :

Balanced chemical reaction : It is defined as the number of atoms of individual elements present on reactant side must be equal to the product side.

The given unbalanced chemical reaction is,

This chemical reaction is an unbalanced reaction because in this reaction, the number of atoms of oxygen are not balanced while all the atoms are balanced.

In order to balanced the chemical reaction, the coefficient 2 is put before the 'Ca' and 'CaO'.

Thus, the balanced chemical reaction will be,

Hence, the correct option is (D) Place a 2 in front of the Ca and the CaO.

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it's c. elements are placed in rows based on how may valencies electrons have.