Best Choice weeks 1-4

Question 1

How do you convert ml to L?

Answer 1

divide the volume value by 1000

Question 2

1000ml = how many litres?

Answer 2

1L

Question 3

What is the numerator?

Answer 3

the number above the line in a vulgar fraction showing how many of the parts indicated by the denominator are taken, for example, 2 in 2/3.

Question 4

What is the denominator?

Answer 4

the number below the line in a vulgar fraction; a divisor.

a figure representing the total population in terms of which statistical values are expressed.

Question 5

How do you calculate the decimal from a fraction?

Answer 5

divide the numerator by the denominator.

Question 6

How do you calculate the percentage from the decimal?

Answer 6

multiply by 100%.

Question 7

How do you calculate percentage by mass?

Answer 7

%A = (m(A)/m(total)) × 100%

Question 8

True or False? isotopes of the same atom have the same chemical properties; however they may react at a slightly different rate.

Answer 8

True

Question 9

How to find the number of protons for an element?

Answer 9

The atomic number is the number of protons in an atom of an element. In our example, krypton’s atomic number is 36. This tells us that an atom of krypton has 36 protons in its nucleus.

Question 10

How to find the number of electrons for an element?

Answer 10

The number of electrons in a neutral atom is equal to the number of protons. aka equal to the atomic number

Question 11

How to find the number of neutrons for an element?

Answer 11

The atomic mass number (usually bottom)- the atomic number (usually top).

Question 12

What are isotopes?

Answer 12

each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass

Question 13

How do we know what isotopes are present and how much of each is present?

Answer 13

This can be accomplished by using a using a mass spectrometer which uses both electric and magnetic fields to sort atoms by atomic mass.

Question 14

How can we use the isotopic composition to calculate the relative atomic mass?

Answer 14

Convert each percentage to a decimal and multiply by the mass number of that isotope. Then add.

Question 15

What is the ‘mole’?

Answer 15

The mole is a measure of the number of formula units of a substance in a sample of a given mass.

Question 16

True or False? the number of formula units in 1 mol of any pure substance is the same as the number of formula units in 1 mol of a different pure substance.

Answer 16

True

Question 17

True or False? The relative masses in grams of samples containing the same amount in moles (the same number of formula units) is the same as the relative masses of the formula units.

Answer 17

True