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Essential Chemistry for IGCSE - Atoms, Elements And Compounds (Section 1)

1
What is a mixture composed of?
Answer
(C)
Two or more substances physically combined
2
What is the name of the two or more atoms that are held together by chemical bonds?
Answer
(D)
molecule
3
What is the unit of relative atomic mass?
Answer
(C)
amu (atomic mass unit)
4
If an atom has 7 protons and 8 neutrons, what is its mass number?
Answer
(D)
15
5
How are elements arranged in the periodic table?
Answer
(C)
By increasing atomic number
6
Which of the following statements is true regarding the arrangement of electrons in an atom?
Answer
(B)
Electrons occupy specific energy levels or shells around the nucleus.
7
What are the components of a compound?
Answer
B
C
8
What happens to an atom when it loses an electron?
Answer
(A)
It becomes a positive ion.
9
Which of the following are elements?
Answer
B
C
10
What is the property that allows metals to be drawn into wires?
Answer
(B)
Ductility
11
What is the role of electrons in chemical reactions?
Answer
(C)
Valence electrons are involved in the reactions.
12
Which of the following are physical properties used to distinguish between metals and non-metals?
Answer
A
B
C
D
13
What is the process of separating a liquid mixture based on different boiling points called?
Answer
(B)
Distillation
14
What does the mass number of an atom represent?
Answer
(C)
The total number of protons and neutrons.
15
What is the charge of a neutron?
Answer
(C)
0
16
What is a molecule?
Answer
(B)
Two or more atoms chemically bonded together
17
What is the relative charge of a proton?
Answer
(B)
+1
18
How many electrons are needed to fill the outermost shell of most atoms?
Answer
(C)
8
19
Which property would be most useful to identify a metal?
Answer
(B)
High melting point
20
Which of the following is a mixture?
Answer
(C)
Air
21
What is a chemical bond?
Answer
(A)
The attraction between two or more atoms
22
Which subatomic particle has a negative charge?
Answer
(C)
Electron
23
How can a mixture be separated?
Answer
(B)
By physical means.
24
Which part of the atom has the smallest mass?
Answer
(C)
Electron
25
What is the best description of a compound?
Answer
(C)
Two or more elements chemically combined
26
What is the process of separating a mixture based on boiling points?
Answer
(B)
Distillation
27
Which of the following is an example of a compound?
Answer
(B)
Table salt (NaCl)
28
Which of the following is a characteristic of nonmetals?
Answer
(C)
They are often gases at room temperature.
29
What is the difference between a physical and a chemical change?
Answer
A
B
30
What does the term 'malleable' mean in the context of metals?
Answer
(B)
Can be hammered into thin sheets
31
What type of particles are found in the nucleus of an atom?
Answer
A
B
32
Which element is used in medical procedures due to radioactive isotopes?
Answer
(C)
Iodine
33
If an element has an atomic number of 17 and a mass number of 35, how many neutrons does it have?
Answer
(B)
18
34
What are isotopes?
Answer
(C)
Atoms with the same number of protons but different numbers of neutrons.
35
How many electrons can the second electron shell hold?
Answer
(C)
8
36
Which of the following is an example of a chemical change?
Answer
(C)
Rusting iron
37
Which of the following is a pure substance?
Answer
(C)
Distilled water
38
What does the Periodic Table arrange elements by?
Answer
(C)
Atomic number
39
What is the name given to the number of protons in the nucleus of an atom?
Answer
(B)
Atomic number
40
Which of the following statements is true about elements?
Answer
(C)
Elements cannot be broken down into simpler substances by chemical reactions.
41
Which state of matter is the most dense?
Answer
(A)
Solid
42
What is a compound?
Answer
(C)
A substance formed when two or more elements are chemically bonded together.
43
How many neutrons are in the isotope of Sodium with a mass number of 23?
Answer
(B)
12
44
Which of the following correctly describes a mixture?
Answer
(C)
A combination of two or more substances that are not chemically combined
45
Which of the following are characteristics of metallic bonds?
Answer
B
C
46
What is the difference between an atom and a molecule?
Answer
(B)
Atoms are the basic building blocks of matter; molecules are formed when atoms combine.
47
What is the total number of atoms present in a molecule of water (H2O)?
Answer
(C)
3
48
What is the formula to determine the number of neutrons in an atom?
Answer
(B)
Mass number - atomic number
49
What is a 'group' in the periodic table?
Answer
(B)
A vertical column of elements.
50
Which of these statements about compounds is TRUE?
Answer
(B)
Compounds always have a fixed composition.