ENTRANCE TEST â€“ 2011 | Multiple Questions and Answers

16.	It is experimentally found that a catalyst is used to:

	A.	Lower the activation energy
	B.	Increase the activation energy
	C.	Lower the pH
	D.	Decrease the temp of the reaction

17.	According to collision theory of bimolecular reaction sin gas phase, the minimum amount of energy required for an effective collision is known as:

	A.	Heat of reaction
	B.	Rate of reaction
	C.	Has no effect on the reaction
	D.	Energy of activation

18.	When elements of group II-A (alkaline earth metals) are exposed to air, they quickly become coated with a layer of oxide. What is the purpose of this oxide layer?

	A.	The oxide layer exposes the metal to Atmospheric attack
	B.	The oxide layer increases the reactivity of metal
	C.	The oxide layer protects the metal from further atmospheric attack
	D.	The oxide layer gives the metal a shiny silvery appearance

19.	In silicon dioxide each silicon atom is tetrahedrally bonded to four oxygen atoms and each oxygen atom is bonded to two silicon atoms. The ratio of silicon to oxygen atoms is:

	A.	2:2
	B.	1:2
	C.	2:1
	D.	1:4