Answer:Hydrogen is placed such because it exhibits some similar characteristics of both group1 and group VII elements.
Explanation:
The reason why hydrogen is similar to group 1 metals:
#It has same valence electron and inorder achieve octet state it can lose that electron and forms H+ ion
#It acts as a good reducing agent similar to group1 metals
#It can also halides
Similarity to halogens:
#hydrogen can also gain one electron to gain noble gas configuration. It can combine with other non metals to form molecules with covalent bonding.
#It exists as diatomin molecule,H2
#Have the same electronegativity nature
#its reaction with other metal
B, Rocks are always being recycled into different forms.
<u>Answer:</u> The balanced half reaction is written below.
<u>Explanation:</u>
Reduction reaction is defined as the chemical reaction in which an atom gains electrons. The oxidation number of the atom gets reduced during this reaction.

When oxygen gas is reduced to oxide ions, the number of electron transferred are 2
The chemical equation for the reduction of oxygen gas to oxide ions follows:

Hence, the balanced half reaction is written above.
Vinegar is a mixture cause its composed of water and acetic acid.
Explanation:
It is given that, Jill and George both push on the same cart with 20 units of force, but in opposite directions.
We know that when two forces are acting in opposite direction, they cancel out each other.
Net force in this case = +20 N - 20 N = 0
It means the net force is 0. As a result, the cart will not move. The forces acting on the cart are balanced.