Chemistry-unit12k15

Question 1

What is the mass number

Answer 1

Number of protons plus neutrons

Question 2

What doesn’t an atom have any charge

Answer 2

This is because they have the same number of positively charged protons in the nucleus, as the number of negatively charged electrons in their shells

Question 3

The periodic tables groups?

Answer 3

This is because they have the same number of electrons in their outer shell (7 electrons) and therefore have similar chemical properties

Question 4

Tick the correct box

Answer 4

Sulphur

Question 5

Particles that include non metal and metals

Answer 5

Ions

Question 6

Particles that include two non metals

Answer 6

Molecules

Question 7

Limestone is calcium ___________. Calcium oxide is produced through ______________ _______________. Calcium hydroxide is created by adding __________

Answer 7

Carbonate
Decomposition
Water

Question 8

How can limestone be used to neutralise acids?

Answer 8

It’s an alkali

Question 9

Line of best fit

Answer 9

Line of best fit

Question 10

How could the accuracy be improved?

Answer 10

By repeating the step shown in figure 2 and calculating an average

Question 11

Estimate the force needed for 0g from the graph?

Answer 11

45N

Question 12

Why isn’t the prediction about the trend correct

Answer 12

Because after 400g , the force needed begins to decrease as for 700g, the force needed is 100N

Question 13

Why are there so many theories?

Answer 13

There is a lack of reliable evidence from the time. Also some evidence conflicts causing many theories

Question 14

Change in the earths surface area and atmosphere

Answer 14

In the early atmosphere, billions of years ago, it is thought that due to intense volcanic activity, in the earths atmosphere, there was a lot of carbon dioxide, water vapour and small proportions of methane and ammonia. However, this changed as the earths atmosphere began to cool down, the water vapour condensed to form oceans. This caused a lot of the carbon dioxide within the air to dissolve into the water and removing lots of it from the atmosphere

Question 15

Why was stage 2 necessary

Answer 15

So that the ore is concentrated meaning that the metal produced will be purified, ridding of any impurities found within the ore. This is why there is a separation so that when the metal is extracted, no impurities will be within

Question 16

Why isn’t cast iron suitable for pylons

Answer 16

It’s too brittle

Question 17

Describe the process shown in the diagram

Cast iron + oxygen –> waste gases + steel

Answer 17

Cast iron is heated in a furnace in the presence of oxygen, so that it can form an alloy with carbon to produce steel

Question 18

Why is aluminium more suitable for pylons than copper

Answer 18

It’s less dense therefore lighter

Question 19

From the periodic table, how can we tell that copper is a transition metal

Answer 19

It is found in group 3 meaning it has only 3 electrons in its outer shell. Moreover, as it is in this certain group, it’s charges of ions can have only one set charge

Question 20

How is copper extracted from copper salts using irons

Answer 20

As iron is more reactive than copper, the scrap iron can displace the copper within the copper ions so that the copper produced will be pure

Question 21

How are fractions of oils separated?

Answer 21

• crude oil enters at the bottom of the fractionating column
• heated at around 350 degrees
• top is cooler, bottom is hotter
• hydrocarbons have different boiling points
• they separate at different boiling points
• they evaporate into a gas and rise till they condense into liquid forms
• they are separated into fractions
• exit out of the tube

Question 22

Suspension of limestone

Answer 22

Sulphur dioxide and nitrogen are slightly acidic and react with calcium carbonate to produce a salt

Question 23

C2H4

Answer 23

C2H4

Question 24

What is the atomic number

Answer 24

Number of protons