Chemistry

Polonium-210 (²¹⁰₈₄Po) is a radioactive isotope that decays by emitting alpha radiation.
Which is the correct decay equation for polonium-210?
Tick (✔) one box.

Why is alpha radiation dangerous inside the human body?
Tick (✔) one box.

Figure 3 shows how the mass of a sample of polonium-210 changes with time.

Determine the change in mass of the sample of polonium-210 between 50 and 150 days.

Using the graph from the previous question, estimate the mass of polonium-210 remaining after 300 days.

Nuclear radiation can cause ionisation.
Complete the sentences. Choose answers from the box.
<br/> <br/>

The ancient Greeks thought that atoms were tiny spheres that could not be divided into anything smaller. Since then, different discoveries have led to the model of the atom changing.
Some of the discoveries are given in Table 1.

Table 1
<br/><br/>

Which discovery was the earliest?
Tick (✔) one box.

Using Table 1 from the previous question, which discovery was the most recent?
Tick (✔) one box.

The alpha particle scattering experiment led to the nuclear model of the atom. Figure 5 shows the paths of alpha particles travelling close to a gold nucleus.

Complete the sentences. Choose answers from the box.
<br/><br/>

The results of the alpha particle scattering experiment were reproducible.
What does reproducible mean?
Tick (✔) one box.

This question is about atoms. Atoms contain three types of particle: electrons, neutrons, and protons. Which particle has no electrical charge?

Which particles have the same relative mass?

The formula of a compound is N₂O. How many of each type of atom are in one molecule of N₂O?

An atom of element Z contains 3 electrons and 3 protons. Give the name of element Z. Use the periodic table.

An atom of element Z contains: 3 electrons, 4 neutrons, 3 protons. Complete the diagram to show the position of the particles in an atom of element Z. Use the symbols: × = electron, ● = neutron, ○ = proton.

The student used a solution of sodium hydroxide of concentration 4.00 g/dm³. Calculate the mass of sodium hydroxide in 25.0 cm³ of this solution. (1 dm³ = 1000 cm³)

This question is about carbon. Which type of substance is carbon?

Carbon has isotopes with mass numbers 12, 13 and 14. Complete the sentences. Choose answers from the box.\n\n[electrons, ions, molecules, neutrons, protons]\n\nThe isotopes of carbon have the same number of ______.\nThe isotopes of carbon have a different number of ______.

12 g of carbon contains 6.02 × 10²³ atoms. Which expression is used to calculate the mass of one atom of carbon?

Carbon exists in different forms called allotropes. Which allotrope of carbon is a simple molecule with the formula C₆₀, forming a shape like a football?

The diagram represents part of the structure of graphite. Which structural feature is the reason that graphite conducts electricity?

The diagram represents part of the structure of graphite. Which structural feature is the reason that graphite is soft?

This question is about alloys. Solders are alloys of tin and lead. The solder in Figure 4 has 6 lead atoms for every 24 tin atoms. Determine the percentage of atoms that are lead atoms in the solder in Figure 4.

Explain why solder is harder than pure tin. Complete the sentences. Use Figure 4.\n\nIn solder the layers are distorted.\nThis is because the atoms of tin and lead have different ______.\nTherefore the layers cannot easily ______.

Describe what happens to the melting point of the solder as the percentage by mass of tin increases. Use data from Figure 5.

What is the melting point of pure tin? Use Figure 5.

What happens to the atoms in pure tin as the tin melts?

This question is about small particles. Which type of particle is often referred to as dust?

A spherical coarse particle has a diameter of 4000 nm. A spherical fine particle has a diameter of 200 nm. How many times larger is the diameter of the coarse particle than the diameter of the fine particle?

Figure 6 represents a cubic nanoparticle with side length 3 nm. The volume of the cubic nanoparticle is 27 nm³. Calculate:\n• the surface area of the cubic nanoparticle\n• the simplest whole number ratio of surface area : volume for the cubic nanoparticle.\nUse the equation: surface area of cubic nanoparticle = 6 × surface area of one face

Titanium oxide is used in some sun creams. Which is an advantage of using nanoparticles of titanium oxide rather than normal-sized particles of titanium oxide in sun creams?