• # question_answer The vector that must be added to the vectors $\hat{j}-3\hat{j}+2\hat{k}$and $3\hat{i}-6\hat{j}-7\hat{k}$so that, the resultant vector is a unit-vector along the Y-axis is A) $4\hat{i}+2\hat{j}+5\hat{k}$                    B) $-4\hat{i}-2\hat{j}+5\hat{k}$                                 C) $3\hat{i}+4\hat{j}+5\hat{k}$                    D) Null vector

Let the desired vector be$\vec{x}.$ $\hat{i}-3j+2\hat{k}+3\hat{i}+6\hat{j}-7\hat{k}+\vec{x}=\hat{j}$or $4\hat{i}+3\hat{j}-5\hat{k}+\vec{x}=\hat{j}$ or, $\vec{x}=-4\hat{i}-2\hat{j}+5\hat{k}$ Hence, the correction option is (b).