Answer 1

// Wrong declaration
int** arr = new int[size_row][size_col]

// Proper declaration
int **arr = new int*[size_row];
for(int i = 0; i < size_row; ++i) {
arr[i] = new int[size_col];
}

// Proper clean up
for(int i = 0; i < size_row; ++i) {
delete [] arr[i];
}
delete [] arr;

for a thorough discussion see [https://stackoverflow.com/questions/936687/how-do-i-declare-a-2d-array-in-c-using-new]