Q1.	A neutral atom of carbon is represented by C.
(i)	Name the constituents of this atom and state how many of each are present.
 (ii)	Which constituent of an atom has the largest charge-to-mass ratio?
 (iii)	Carbon has several isotopes. Explain the term isotope.
 (Total 6 marks)

Q2.	(a)	Th is a neutral atom of thorium.  How many protons, neutrons and electrons does it contain?	
(2)
(b)	Th is a neutral atom of a different isotope of thorium which contains Z electrons.  Give possible values for X, Y and Z.	
(3)
(Total 5 marks)
Q3.	(a)	The most abundant isotope of cobalt is represented by .
	How many protons, neutrons and orbital electrons are there in a neutral atom of this element?
 (2)
(b)	How is the nuclide that has one less proton than the nickel nuclide, , represented?
(2)
(c)	(i)	The heaviest isotope of hydrogen, whose nucleon number is 3, is called tritium. How is tritium represented?
 (ii)	Calculate the charge per unit mass, in C kg–1, for a tritium nucleus.
 (3)
(Total 7 marks)
Q4.	An atom of argon  is ionised by the removal of two orbiting electrons.
(a)	How many protons and neutrons are there in this ion?
 (2)
(b)	What is the charge, in C, of this ion?
 (2)

(c)	Which constituent particle of this ion has
(i)	a zero charge per unit mass ratio,
 (ii)	the largest charge per unit mass ratio?
 (2)
(d)	Calculate the percentage of the total mass of this ion that is accounted for by the mass of its electrons.
 (3)
(Total 9 marks)
Q5.	A radioactive isotope of carbon is represented by C.
(a)	Using the same notation, give the isotope of carbon that has two fewer neutrons.
 (1)
(b)	Calculate the charge on the ion formed when two electrons are removed from an atom of C.
 (2)
(c)	Calculate the value of  for the nucleus of an atom of C.
 (2)
(Total 5 marks)

Q6.	(a)	How many protons, neutrons and electrons are there in an atom of ?
 (2)
(b)	The  atom loses two electrons.
For the ion formed;
  (i)	calculate its charge in C,
 (ii)	state the number of nucleons it contains,
 (iii)	calculate the ratio  in C kg–1.
 (4)
(Total 6 marks)
        Q7.	(a)	An ion of plutonium Pu has an overall charge of +1.6 × 10–19C.
	For this ion state the number of
(i)	protons             (ii)	neutrons             (iii)	electrons
(3)
   (b)	Plutonium has several isotopes.
	Explain the meaning of the word isotopes.
 (2)
(Total 5 marks)
Q8.	(a)	Name the constituent of an atom which
(i)	has zero charge,
 (ii)	has the largest charge to mass ratio,
 (iii)	when removed leaves a different isotope of the element.
 (3)
(b)	An  particle is the same as a nucleus of helium, He.
The equation
Th     Ra   +   
	represents the decay of thorium by the emission of an  particle.
	Determine
(i)	the values of X and Y, shown in the equation,

(ii)	the ratio
 (3)
(Total 6 marks)
Q9.	(a)	A stable atom contains 28 nucleons.
Write down a possible number of protons, neutrons and electrons contained in the atom.
 (2)
(b)	An unstable isotope of uranium may split into a caesium nucleus, a rubidium nucleus and four neutrons in the following process.

(i)	Explain what is meant by isotopes.
 (ii)	How many neutrons are there in the Cs nucleus?
 (iii)	Calculate the ratio, in C kg–1, for the U nucleus.

(iv)	Determine the value of X for the rubidium nucleus.
 (6)
(Total 8 marks)

Q10.	(a)	Give the number of nucleons and the number of electrons in an atom of Na.
 (2)
(b)	The isotope Na is a positron emitter.  In positron emission an up quark undergoes the following change,
u    d  +  +  +  ve.
	Show that charge, lepton number and baryon number are conserved in this decay.
 (3)
(c)	Describe what happens when a positron collides with an electron.
 (2)
(Total 7 marks)
Q11.	(a)	(i)	Determine the charge, in C, of a  nucleus.

(ii)	A positive ion with a  nucleus has a charge of 4.80 × 10–19 C.
Determine how many electrons are in this ion.
 (4)
(b)	A  nucleus may decay by emitting two – particles to form a plutonium nucleus . State what X and Y represent and give the numerical value of each.
 (4)
(Total 8 marks)