The metalloids in the second and third periods

Answer the following questions: How many elements are there in the second and the third periods of the periodic table ?

Match the first column with appropriate entries in the second and third columns and remake the table:

Name the following: The three metals in the third period of the modern periodic table.

The ratio of the difference in energy between the first and the second and the third Bohr orbit is

If three numbers are added the sum is 15. If the second number is subtracted from the sum of first and third number then we get 5 and if twice the first number is added to the second and the third number is subtracted from the sum we get 4 . Use matrices to find the numbers.

The first elements of first second and third transition series respectively are

The sum of three numbers is 6.Thrice the third number when added to the first number gives 7. On adding three times first number to the sum of second and third number we get 12. Find the three numbers by using Matrices.

Non-metals in the third period .