Biology
Chemistry
Physics
100
What is the role of the transport system
Providing the body with subtances
100
The equation for chromatography
200
The function of mitochondria.
Most energy is released in respiration.
200
Balance these chemical equations:
a) H2 + O2 --> H2O
b) Al + O2 --> Al2O3
a. 2H2 + O2 -> 2H2O
b. 4Al + 3O2 -> 2AlO3
200
Which of the two following would also increase the braking distance of the car?
1. rain on the road
2. the driver having drunk alcohol
3. car brakes in bad condition.
4. the driver having taken drugs
1 and 3
300
Calculate images sizes: Magnification, Size of image (observe) and Size of real object.
Magnification = size of image (observe) / real object
Size of image (observe) = magnification x real object
Size of real object = size of image (observe) / magnification
300
Distinguish the differences between the elements, compounds, and mixtures.
Element: made up of only one type of atom.
Compound: a pure substance made from two or more elements chemically bonded together.
Mixtures: more than one substance, may be in different physical states.
300
In the motor, the electrical energy is transferred into other types of energy. Some of this energy is useful and the rest of the energy is wasted.
a) Name the useful energy output from the electric motor.
b) What eventually happens to the wasted energy?
a) kinetic energy
b) dissipates into the surroundings.
400
Sometimes food additives are added to yogurt. Some people suggest that it is healthier to eat yogurt without additives.
Suggest advantages and disadvantages of putting food additives into yogurt.
Advantages:
- Longer shelf-life
- Stop/reduce the growth of unwanted bacteria.
Disadvantages:
- Hyperactivity
- Allergies
400
1. Explain the term amphoteric.
2.Name the two reagents that are needed to show that an oxide is amphoteric.
1. shows both basic and acidic properties.
2. the names of a strong acid and alkali.
400
A car driver sees a fallen tree lying across the road ahead and makes an emergency stop.
The braking distance of the car depends on the speed of the car.
For the same braking force, explain what happens to the braking distance if the speed doubles.
You should refer to kinetic energy.
- Double speed increases kinetic energy.
- Kinetic energy increases by a factor of 4
- Work done to stop the car decreases.
- Work done is force x distance and braking force is constant -> increases by 4 then distance increases by 4.
500
On a summer day, 175 000 joules of energy are supplied to the aircraft's solar cells every second. The useful energy transferred by the solar cells is 35 000 joules every second.
(i) use the formula of calculating the efficiency to answer, show your work.
(ii) what happens to the energy that is not useful transferred by the solar cell.
(i) 0.2 or 1/5
(ii) wasted or transformed to heat or air/other forms.