The sentences are invalid and unsound.
<h3><u>Explanation</u>:</h3>
The fire is defined as the vigorous oxidation of a substance. Now oxidation can occur in presence of any oxidising agent. Like magnesium in presence of nitrogen in high temperature with a dazzling brownish flame to produce magnesium nitride. So fire can be produced in absence of oxygen.
Oxygen is present everywhere in world. So production of a whole room without oxygen is very tough to produce and costly process. So its very unsound.
I believe that the statement above is TRUE. I can say that it's true because based on the definition of what reciprocal liking is, this is the probability of having to like someone who also likes them in return. Therefore, if they like each other, this means that there is a low risk of rejection in the relationship.
Water must absorb energy in order to melt, evaporate, or get warmer.
Answer:
The focal length of the mirror is 52.5 cm.
Explanation:
Given that,
Object to Image distance d = 140 cm
Image distance v= 35 cm
We need to calculate the object distance


We need to calculate the focal length
Using formula of mirror

Put the value into the formula



Hence, The focal length of the mirror is 52.5 cm.