1. 1
   The mean distance from the Earth to the Sun is $1.5\times10^{11}$ m and the mean distance from Neptune to the Sun is $4.5\times10^{12}$ m. Light travels at $3.0\times10^{8}$ m s$^{-1}$.

   (a)

   Find the time, in seconds, for light to travel from the Sun to the Earth.

   [1 mark]

   • A$5.0\times10^{3}$
   • B$5.0\times10^{2}$
   • C$2.0\times10^{-3}$
   • D$4.5\times10^{19}$

   (b)

   How many times further from the Sun is Neptune than the Earth?

   [1 mark]

   • A$3.0\times10^{23}$
   • B$3.0\times10^{-1}$
   • C$3.0\times10^{1}$
   • D$6.75\times10^{23}$

   (c)

   Find the difference between the distance from Neptune to the Sun and the distance from the Earth to the Sun. Give your answer in the form $a\times10^{k}$, where $1\le a<10$ and $k\in\mathbb{Z}$.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A human red blood cell has a diameter of approximately $8\times10^{-6}$ m. A typical adult has about $2.5\times10^{13}$ red blood cells and $5.0\times10^{3}$ millilitres of blood. One nanometre is $10^{-9}$ m.

   (a)

   The red blood cells of one adult are placed in a single line, touching end to end. Find the total length of the line in metres.

   [1 mark]

   • A$2\times10^{20}$
   • B$2\times10^{7}$
   • C$3.125\times10^{18}$
   • D$2\times10^{8}$

   (b)

   Find the diameter of a red blood cell in nanometres.

   [1 mark]

   • A$8\times10^{3}$
   • B$8\times10^{-15}$
   • C$1.25\times10^{-4}$
   • D$8\times10^{-3}$

   (c)

   Find the mean number of red blood cells in one millilitre of blood. Give your answer in the form $a\times10^{k}$, where $1\le a<10$ and $k\in\mathbb{Z}$.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A data centre has a total storage capacity of $3.6\times10^{17}$ bytes. A single high-resolution photograph uses $4.5\times10^{6}$ bytes of storage. Users upload $1.5\times10^{8}$ photographs to the centre every day. The centre starts empty.

   (a)

   Find the maximum number of photographs the data centre can store. Give your answer in the form $a\times10^{k}$, where $1\le a<10$ and $k\in\mathbb{Z}$.

   [3 marks]

   (b)

   Find the number of the day on which the data centre first becomes full. Justify your answer.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   Country P has a population of $6.4\times10^{7}$ and its total annual carbon dioxide emissions are $3.2\times10^{11}$ kg. Country Q has a population of $1.4\times10^{9}$ and its total annual carbon dioxide emissions are $1.05\times10^{13}$ kg.

   (a)

   (i) Find the annual carbon dioxide emissions per person for country P and for country Q.
   (ii) Find the total population of the two countries and the total annual emissions of the two countries.
   Give each answer in the form $a\times10^{k}$, where $1\le a<10$ and $k\in\mathbb{Z}$.

   [6 marks]

   (b)

   Country Q sets a target to reduce its total annual emissions so that its emissions per person equal the current emissions per person of country P, with its population unchanged. Find the reduction in Q's total annual emissions required, and show that this reduction is more than ten times the current total annual emissions of country P.

   [6 marks]

   Total for question 4: 12 marks

End of questions