Find the number of matrices having 12 elements

The number of matrices having 7 elements is……………

A is a 3 xx 3 matrix whose elements are from the set { -1, 0, 1} . Find the number of matrices A such that tr(AxxA^T) =3 . Where tr(A) is the trace of A.

Out of the first 100 elements the number of elements having electrons in the 3d orbital are

Find the number of integers which lie between 1 and 10^6 and which have the sum of the digits equal to 12.

Consider the following elements B C F Cl N O If x,y and z are the number of elements having more electron affinity (Ea_(1)) than nitrogen, the number of elements having ionisation energy more than that of Na and the number of elements having electronegativity more than (or) almost equal to N respectively, find x+y+z . Fill your answer as sum of digit (excluding decimal places) till you get the single digit answer.

Find the number of g atoms and weight of an element having 2 xx 10^(23) atoms. Atomic mass of element is 32.

Find the number of g atoms and weight of an element having 2 xx 10^(23) atoms. Atomic mass of element is 32.

Find the sum of 8 numbers with mean 12.

Up to atomic number 19 ,if' X number elements are having positive electron gain enthalpy (EGE_(1)) and Y number of elements are having negative electron gain enthalpy (EGE_(1)) then find the value of (X)/(Y) ?

An nxxn matrix is formed using 0,1 and -1 as its elements. The number of such matrices which are skew-symmetric, is