CHEMISTRY

Question 1

Table 1 shows the proton number, nucleon number and number of electrons for four particles.

Which pair of particles are isotopes of the same element?

Accepted Answer

0

Question 2

Which isotope is used by doctors to detect and treat thyroid disease?

Accepted Answer

2

Question 3

Which pairing of isotopes and their use is correct?

Accepted Answer

2

Question 4

What is the use of isotopes cobalt-60 and iodine-131

Accepted Answer

2

Question 5

Isotopes are atoms of the same element with the same number of protons but different number of neutrons

Accepted Answer

o

Question 6

State one use for the isotopes Sodium-24.

Accepted Answer

Detecting leakage

Accepted Answer

Detecting leakage in underground pipes

Question 7

Magnesium exists naturally as three isotopes, which are 79% of Magenesium-24, 10% of Magnesium-25 and 11% of Magnesium-26.

Calculate the relative atomic mass of magnesium.

Accepted Answer

24.32

Question 8

Figure 1 shows a graph of temperature against time for vapour X as it is cooled until it becomes a solid.

Name the process of change in state of matter when vapour X is cooled.

Accepted Answer

sublimation

Question 9

Determine the number of valence electrons for the atoms in Figure 2.18

Accepted Answer

1

Question 10

A chlorine atom has 17 protons and 18 neutrons. What is the proton number and nucleon number of the chlorine atom?

Accepted Answer

Proton 17 nucleon 35

Accepted Answer

protons 17 nucleon 35

Accepted Answer

proton number 17 nucleon number 35

Question 11

Unsur X has a boiling point of -34 degree celcius.

What is the physical state of element X at a room temperature?

Accepted Answer

1

Question 12

The following are four steps in scientific investigation.

Which sequence is correct

Accepted Answer

1

Question 13

If your friend's eye comes in contact with a chemical, what is the first action that you must do?

Accepted Answer

2

Question 14

Iron atom has proton number 26 and nucleon number 56. Iron atom loses 3 electrons to form an ion. What is the number of each subatomic particle in the iron ion?

Accepted Answer

Proton 26, Neutrons 30, Electron 23

Accepted Answer

26,30,23

Question 15

In the experiment of cooling naphthalene. Why the naphthalene need to be stirred continuosly?

Accepted Answer

Avoid supercooling

Accepted Answer

Supercooling