The answer would be letter A.Among the alkali earth metals, the tendency to react with other substances <span>increases from bottom to top within the group. We know that when there is an increase of metallic property, there will also be an increase of reactivity. </span>
Answer:
According to Bronsted-lowry concept an acid is a hydrogen donnor and a base is a hydrogen acceptor.
Explanation:
Herd behavior in elephants ensures that individuals are protected and the species is perpetuated.
<h3>What is her behavior?</h3>
It is a behavior that is characteristic of animals that form herds.
Herds generally refer to groups of animals that live or move together or both.
By protecting individual elephants that are weak or young from being preyed upon by lions and leopards, more members of the population survive.
When more members of the population survive, the species is perpetuated and the likelihood of going into extinction reduces.
More on herd behavior can be found here: brainly.com/question/15112922
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Answer : The correct option is, (B) 
Solution :
According to the Graham's law, the rate of effusion of gas is inversely proportional to the square root of the molar mass of gas.

or,
..........(1)
where,
= rate of effusion of unknown gas = 
= rate of effusion of oxygen gas = 
= molar mass of unknown gas = ?
= molar mass of oxygen gas = 32 g/mole
Now put all the given values in the above formula 1, we get:


The unknown gas could be carbon dioxide
that has approximately 44 g/mole of molar mass.
Thus, the unknown gas could be carbon dioxide 