Which of the following compounds will leave a metal residue when heated?

• A. Cu(NO₃)₂
• B. AgNO₃
• C. K2CO₃
• D. CaCO₃

Which of the following statements is not correct? The 4s orbital

• A. is defined by the quantum number 1 = O
• B. is of higher energy than the 3d orbital
• C. contains a maximum of two electrons
• D. is spherical about the nucleus

A few drops of NaOH solution was added to an unknown salt forming a white precipitate which is insoluble in excess solution. The cation likely present is

• A) Zn2+
• B) Pb2+
• C) Ca2+
• D) Al3+

Consider the following elements and their electronic configurations W: 1s²2s² X: 1s²2s²2p⁶ Y: 1s²2s²2p⁶3s² Z: 1s²2s²2p⁶3s²3p². Which of the elements belong to the same group in the periodic table?

• A. W and X only
• B. Y and Z only
• C. W and Y only
• D. W, Y and Z only

Consider the following equation; Cr₂O₇(aq)^2- + 14H⁺(aq) + 6e^- → 2Cr³⁺(aq) + 7H₂O(I). The oxidation number of chromium changes from

• A. -2 to + 3
• B. - 2 to + 6
• C. + 6 to + 3
• D. + 7 to + 6

An electron can be added to a halogen atom to form a halide ion with

• A. 2 valence electrons
• B. 3 valence electrons
• C. 7 valence electrons
• D. 8 valence electrons

The ratio of the number of molecules in 2g of hydrogen to that in 16g of oxygen is

• A) 2:1
• B) 1:1
• C) 1:2
• D) 1:4

In an endothermic reaction, if there is a loss in entropy the reaction will

• A) be indeterminate
• B) be spontaneous
• C) not be spontaneous
• D) be at equilibrium

120cm\(^3\) of hydrogen were sparked with 60cm\(^3\) of oxygen at 110°C. What was the volume of swam produced? The equation for the reaction is 2H\(_2\)(g) + O\(_2\)(g) \(\rightarrow\) 2H\(_2\)(g)

• A) 30cm
• B) 60cm
• C) 90cm
• D) 120cm

The pH of a solution obtained by mixing 100cm³, 0.1M HCl solution with 100cm³ of a 0.2M solution of NaOH is

• A) 1.3
• B) 7.0
• C) 9.7
• D) 1.7