State true or false. Vanmathi bought $4$ books each weighing \[500g\]. The weight of $4$ books is $2kg$.
A) True
B) False

Hint: We are given the weight of each book. So we can find the weight of four books by multiplying the given weight by four. Then we get the statement is true or false according to the calculated weight.

Formula used: One kilogram is equal to thousand grams, $1kg = 1000g$
Weight of $n$ products of the same kind is equal to $n$ times weight of one product.

Complete step-by-step answer:
 Vanmathi bought $4$ books each weighing \[500g\].
Weight of $n$ products of the same kind is equal to $n$ times weight of one product.
So we get, the weight of $4$ books is equal to $4$ times weight of one book.
Here we can substitute $4$ for $n$ and $500g$ for the weight of one book.
Therefore we have,
${\text{weight of 4 books = 4}} \times {\text{500g = 2000g}}$
We know that, One kilogram is equal to a thousand grams.
So we get $2000g = 2kg$
This gives the weight of $4$ books is $2kg$.
So the given statement is true.

$\therefore $ The answer is option A.

Note: Since $500g$ is half a kilogram we get, four times half kilogram as two kilogram. Weight of $n$ products of the same kind is equal to $n$ times weight of one product. So it is important that the products are identical. If the four books bought were of different weight, we cannot simply multiply as we did to find the weight of four books. Instead we have to add the weight of four books separately. But in this question, it is said that each book weighs half kilogram.