Chemistry S2 Test Review Juniors - 2024

How many electrons does an atom generally need in its outer level to be most stable?

• 16

• 12

• 4

• 8

Which energy level of the period 4 transition elements is being filled with electrons?

• 6th

• 5th

• 4th

• 3rd

How many sigma and how many pi bonds are present in the ethene molecule (C2H4)?

• 4 sigma & 1 pi

• 5 sigma & 2 pi

• 4 sigma & 2 pi

• 5 sigma & 1 pi

Calculating the mass of a reactant and product from the number of moles of another product or reactant in a chemical equation is an example of a _____.

• mass-to-mole conversion

• mole-to-mole conversion

• mole-to-mass conversion

• mass-to-mass conversion

Limiting a reactant is often accomplished by _____.

• slowing down a chemical reaction

• producing excess product

• overcoming conservation of mass

• using an excess of another reactant

In a balanced chemical equation, the numbers of individual particles and the numbers of moles of particles are represented by the _____.

• subscripts

• coefficients

• chemical symbols

• molar masses

What is the formula of calcium phosphate, which is made up of the ions Ca2+ and PO43-?

• Ca3(PO4)3

• Ca6PO4

• Ca3(PO4)2

• Ca3PO4

Ion X has a charge of 2+, and ion Y has a charge of 1-. What is the formula unit of the compound formed from the ions?

• XY

• X2Y

• X2Y3

• XY2

Which of the following elements normally exists in the form of diatomic molecules?

• helium

• argon

• iron

• nitrogen

In the ionic solid sodium chloride (NaCl), there is a _____ ratio of sodium ions to chlorine ions.

• two to one

• one to one

• one to two

• one to one half