Bio.
In photosynthesis, water is split to produce oxygen. Name the process in which water is split.
photolysis
Give the chemical test for hydrogen gas
Lit splint → squeaky pop
What is mass
quantity that measures the amount of matter in an object
What is the only metal that is liquid at room temperature
Mercury
Name the Southeast Asian country that experiences some of the world’s worst monsoon flooding and has the Ganges–Brahmaputra delta.
Bangladesh
What type of bond that holds the two strands of DNA together
hydrogen bond
A student reacts 12 g of magnesium with excess hydrochloric acid.
Mg + 2HCl → MgCl₂ + H₂
Calculate the number of moles of hydrogen produced.
0.5 mol H₂
Explain why light bends when passing from air into water.
because of refraction due to change in speed of light between medium
Which organ in the human body can regenerate itself
Liver
Name the country described: It has a very high dependency ratio, declining birth rate, shrinking workforce, and the world’s highest life expectancy. It also relies heavily on imported raw materials.
Japan
A plant cell placed in a solution increases in mass by 12%. The initial mass was 2.5 g. Calculate the final mass and state whether the solution was hypotonic or hypertonic.
2.8 g; hypotonic
What type of reaction occurs when an acid reacts with a base to form a salt and water
neutralisation
State the formula for density
Density = mass / volume
Which planet rotates in the opposite direction to most planets
Venus
Name the country famous for the Three Gorges Dam, rapid industrial growth, and severe air pollution issues.
China
A student dilutes a 2 mg cm⁻³ starch solution to make 250 cm³ of a 0.25 mg cm⁻³ working solution. Calculate the volume of stock required and volume of water added.
31.25 cm³; 218.75 cm³
A hydrocarbon contains 85.7% carbon and 14.3% hydrogen by mass. Molar mass = 56 g mol⁻¹. Determine the empirical formula and molecular formula.
C₄H₈
A 12 V supply is connected to a 4 Ω resistor and a 6 Ω resistor in series. Calculate (1) the total current, (2) potential difference across the 6 Ω resistor.
1.2 A; 7.2 V
Why does rate of diffusion increase at higher temperatures
Particles have higher kinetic energy → faster random motion
Which country has the world’s lowest population density
Mongolia
Yeast population doubles every 2 hours. If the starting population is 5×10⁴ cells, calculate the population after 8 hours, and express the answer in standard form.
8.0×10⁵ cells
Calculate the pH of a weak acid HA where Ka = 1.7×10⁻⁵ and initial concentration = 0.040 mol dm⁻³.
Assume [H⁺] ≈ √(Ka × c).
3.08
A 3 kg object is pulled by a force of 18 N at 30° above the horizontal. Calculate the horizontal acceleration and the normal force on the object.
5.2 m/s²; 20.4 N
Why does a catalyst not affect equilibrium yield
It speeds forward and backward reactions equally
Cyclone Nargis (2008) devastated this Southeast Asian country
Myanmar