Is it possible to have a polyhedron with any given number of faces?(Hint:Think of a pyramid).

Is it possible to have an element with atomic number 1.5 placed between hydrogen and helium?

Can a polyhedron have 10 faces,20 edges and 15 vertices?

(c ) Given n students in the class like football, what may 2n show? What may n/2 show? (Hint: Think of games other than football).

(a)Look at the following matchstick pattern of squares (Fig 11.6). The squares are not separate. Two neighbouring squares have a common matchstick. Observe the patterns and find the rule that gives the number of matchsticks in terms of the number of squares. (Hint: If you remove the vertical stick at the end, you will get a pattern of Cs.)

(a)Look at the following matchstick pattern of squares (Fig 11.6). The squares are not separate. Two neighbouring squares have a common matchstick. Observe the patterns and find the rule that gives the number of matchsticks in terms of the number of squares. (Hint: If you remove the vertical stick at the end, you will get a pattern of Cs.)(c)

(a)Look at the following matchstick pattern of squares (Fig 11.6). The squares are not separate. Two neighbouring squares have a common matchstick. Observe the patterns and find the rule that gives the number of matchsticks in terms of the number of squares. (Hint: If you remove the vertical stick at the end, you will get a pattern of Cs.)(d)

(a) Given Munnu's age to be x years, can you guess what (x-2) may show? (Hint: Think of Munnu's younger brother.) Can you guess what (x+4) may show? What (3x+7) may show?

Ten different letters of an alphabet are given . Words with five letters are formed from these given letters. Then the number of wards which have at least one letter repeated is :