How many orbitals are in the d-sub shell?

A. 1

B. 3

C. 5

D. 7

An element X has isotopic masses of 6 and 7. if the relative abundance is 1 to 12.5 respectively, what is the relative atomic mass of X?

A. 6.0

B. 6.1

C. 6.9

D. 7.0

An atom ²³⁸₉₂X decays by alpha particle emission to give an atom Y. The atomic number and mass number of Y are

A. 90 and 234 respectively

B. 91 and 238 respectively

C. 92 and 236 respectively

D. 93 and 238 respectively

If 1 mole of sodium contains 6 x 10²³ atoms, how many atoms are contained in 0.6 g of sodium? [Na = 23]

A. 1.56 x 10²³

B. 1.56 x 10²²

C. 3.6 x 10²³

D. 3.6 x 10²²

If 20 cm³ of distilled water is added to 80cm ³ of 0. 50 mol dm^-3 hydrochloric acid, the new concentration of the acid will be

A. 0.10mol dm^-3

B. 0.20mol dm^-3

C. 0.40mol dm^-3

D. 2.00mol dm^-3

Consider the reaction represented by the equation. 2NaHCO_3(s) \(\rightarrow\) 2Na₂CO _3(S) + CO _2(g) + H₂O_(g) what volume of carbon (IV)oxide at s.t.p is evolved when 0. 5 moles of NaHCO₃ is heated? [Molar volume = 22.4 dm³ at s.t. p]

A. 1.12dm³

B. 2.24dm³

C. 5.6dm³

D. 56.0dm³