`3647-:13`

Show that Balmer series appears between 3647Å and 6563Å in the hydrogen spectrum.

4/13+9/13+2/13=-/13

7/13+(-9)/13=(__+(-9))/13=-/13

Show that the three lines with direction cosines 12/13,(-3)/13,(-4)/13 , 4/13,12/13,3/13 , 3/13, (-4)/13,12/13 , are mutually perpendicular .

Show that the three lines with direction cosines 12/13, -3/13, -4/13, 4/13, 12/13, 3/13, 3/13, -4/13, 12/13 are mutually perpendicular.

Show that the three lines with direction cosines 12/13,-3/13,-4/13,4/13,12/13,3/13,3/13,-4/13,12/13 are mutually perpendicular.

Solve the following 7/13 + -9/13 = (--+(-9))/13 = (---)/13

The value of 13C_7+13C_8+13C_9+13C_10+13C_11+13C_12+13C_13 is equal to

3/13-2/13+5/13 =