level 1
25.What is the chemical formula for methane?
a) CO₂
b) H₂O
c) CH₄
d) NH₃
Answer: c) CH₄
24.Which element has a full valence electron shell naturally?
a) Hydrogen
b) Helium
c) Carbon
d) Sodium
Answer: b) Helium
wer: b) Chlorine
15.Which type of formula shows the arrangement of atoms in a molecule?
a) Chemical formula
b) Structural formula
c) Empirical formula
d) Molecular formula
Answer: b) Structural formula
Which type of covalent bond involves three shared pairs of electrons?
a) Single
b) Double
c) Triple
d) Quadruple
Answer: c) Triple
Which of the following is a chemical formula?
a) H—H
b) O₂
c) C≡C
d) NaCl
Answer: d) NaCl
23.Why do atoms form covalent bonds?
a) To lose mass
b) To become electrically charged
c) To achieve a noble gas electron configuration
d) To release energy
Answer: c) To achieve a noble gas electron configuration
Which bond type shares only one pair of electrons?
a) Single bond
b) Double bond
c) Triple bond
d) Metallic bond
Answer: a) Single bond
Which element is most likely to form covalent bonds?
a) Sodium
b) Chlorine
c) Neon
d) Argon
Answer: b) Chlorine
Which of the following molecules is polar?
a) O₂
b) CO₂
c) H₂O
d) CH₄
Answer: c) H₂O
What does CO₂ represent?
a) 2 carbon atoms and 1 oxygen
b) 1 carbon atom and 2 oxygen atoms
c) 3 atoms of the same element
d) 1 carbon atom bonded with 1 oxygen
Answer: b) 1 carbon atom and 2 oxygen atoms
21.What does a triple bond look like in a structural formula?
a) A single line between atoms
b) A double line between atoms
c) Three lines between atoms
d) No lines between atom
Answer: c) Three lines between atoms
Which of the following diagrams shows valence electrons in atoms?
a) Dot diagram
b) Space-filling model
c) Ball-and-stick model
d) Structural formula
Answer: a) Dot diagram
What are valence electrons responsible for?
a) Identity of an element
b) Atomic mass
c) Chemical properties and reactivity
d) Neutron count
Answer: c) Chemical properties and reactivity
What does a subscript in a chemical formula indicate?
a) Number of atoms of the element
b) Charge of the molecule
c) Number of bonds
d) Type of element
Answer: a) Number of atoms of the element
What type of bond is created by sharing electrons?
a) Ionic
b) Covalent
c) Metallic
d) Van der Waals
Answer: b) Covalent
18.Which type of bond results in a stable noble gas configuration?
a) Ionic bond
b) Metallic bond
c) Covalent bond
d) Hydrogen bond
Answer: c) Covalent bond
19.What is the chemical formula of water?
a) H₂
b) H₂O
c) O₂
d) CO₂
Answer: b) H₂O
How many pairs of electrons are shared in a double covalent bond?
a) 1
b) 2
c) 3
d) 4
Answer: b) 2
How many atoms of oxygen are present in H₂O?
a) 1
b) 2
c) 3
d) 4
Answer: a) 1
Which subatomic particle is involved in bonding?
a) Proton
b) Neutron
c) Valence electron
d) Nucleus
Answer: c) Valence electron
17.How many atoms of hydrogen are in CH₄?
a) 1
b) 2
c) 3
d) 4
Answer: d) 4
Which molecular model provides a 3D representation of atomic connections?
a) Dot diagram
b) Ball-and-stick model
c) Space-filling model
d) Lewis structure
Answer: c) Space-filling model
What type of molecular model represents atoms connected by sticks?
a) Dot diagram
b) Ball-and-stick model
c) Space-filling model
d) Structural formula
Answer: b) Ball-and-stick model
What is a covalent bond?
a) A bond formed by transferring electrons
b) A bond formed by sharing electrons
c) A bond formed by losing protons
d) A bond involving neutrons
Answer: b) A bond formed by sharing electrons
What determines an element's identity?
a) Neutrons
b) Protons
c) Electrons
d) Valence electrons
Answer: b) Protons