Scalar Matrix

Q.

Which among the following is a scalar matrix?

1. $\left[\begin{array}{cc}1& 0\\ 0& 1\end{array}\right]$

2. $\left[\begin{array}{cc}0& 2\\ 2& 0\end{array}\right]$

3. $\left[\begin{array}{cc}5& 5\\ 5& 5\end{array}\right]$

4. $\left[\begin{array}{cc}0& 0\\ 1& 1\end{array}\right]$

Q. Which of the following is/are a function defined from A to A, where A = {a, b, c}?
निम्नलिखित में से कौनसा/कौनसे विकल्प A से A तक परिभाषित एक फलन है/हैं, जहाँ A = {a, b, c} ?

1. {(a, a), (b, a), (c, a)}
2. {(a, c), (c, a)}
3. {(a, a), (b, c)}
4. {(a, a), (a, b), (a, c)}

Q.

If k is scalar $(k\ne 0)$, I is an identity matrix and A is a square matrix . Then which among the following will always be a scalar matrix.

1. $kA$

2. $kI$

3. $\frac{1}{k}.A$

4. $\frac{1}{k}.I$