Question 1: Define isotopes and explain how they differ from each other.

Answer: Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons.

Question 1: What is the notation used to represent isotopes, including their mass number and atomic number?

Answer: The notation is written as element symbol with mass number as a superscript and atomic number as a subscript, e.g., ¹³₆C for Carbon-13.

Question 2: Explain why isotopes of the same element have similar chemical properties but different physical properties.

Answer: Because they have the same number of electrons and similar electronic structure, so they react similarly chemically. However, different neutrons affect physical properties like density and stability.

Question 1: Calculate the relative atomic mass of an element that consists of 75% of isotope A with a mass of 20 u, and 25% of isotope B with a mass of 22 u.

Answer: ((75/100) * 20) + ((25/100) * 22) = 15 + 5.5 = 20.5 u

Question 2: An isotope of sulphur has 16 protons and 18 neutrons. Write its isotope notation and calculate its atomic mass number.

Answer: ¹⁸S; atomic mass number = 16 + 18 = 34

Question 1: Describe a simple experiment to demonstrate the existence of isotopes in a sample of an element.

Answer: Separate the sample using mass spectrometry to observe different isotopic masses, indicating the presence of isotopes.

Question 2: List two safety precautions that should be considered when handling radioactive isotopes in a laboratory setting.

Answer: Use appropriate shielding and wear protective clothing to prevent radiation exposure.

Question 1: A sample of an element has two isotopes. Isotope X makes up 60% of the sample with a mass of 35 u, and isotope Y makes up 40% with a mass of 37 u. Calculate the average atomic mass of the element.

Answer: ((60/100) * 35) + ((40/100) * 37) = 21 + 14.8 = 35.8 u

Question 1: Explain how isotopic differences can be used in radiocarbon dating. (6 marks)

Answer: Isotopic differences, specifically the ratio of carbon-14 to carbon-12, are used in radiocarbon dating because living organisms maintain a constant ratio. When an organism dies, the carbon-14 decays at a known rate, allowing scientists to estimate the time since death by measuring the remaining isotope ratio.

Question 1: Describe how isotopes are used in medical imaging or treatment.

Answer: Radioisotopes such as iodine-131 are used in medical imaging and treatment because they emit radiation that can be detected or used to target diseased tissues.