7. Which of the following combination will produce H2 gas? 8. (a) Zn metal and NaOH(aq) (b) Au metal and NaCN(aq) in the presence of air (c) Cu metal and conc. HNO3 (d) Fe metal and conc. HNO3 Which one of the following is an inner orbital complex as well as diamagnetic in behavior? (a) [Zn(NH3)+ (b) [Ni(NH3)6]+ (c) [Cr(NH3)]+ (d) [Co(NH,),] 9. FeCl3 + Potassium thiocynate (a) Red product, the colour of this product is : (b) Chocolate colour (c) Prussian blue (d) Colourless 10. Which of the following can react with both HCl and NaOH ? (a) Zn(OH)2 (b) BeO (c) Al2O3 (d) All of these