21.
Which of the following particles are found in the nucleus of an atom?
A
Only neutrons
B
Electrons and neutrons
C
Protons and neutrons
D
Electrons and protons
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Which of the following particles are found in the nucleus of an atom?
Only neutrons
Electrons and neutrons
Protons and neutrons
Electrons and protons
What is an atom?
The smallest particle of an element
A particle of a compound
A type of molecule
A part of a molecule
Which of the following is a technique used to separate different colored pigments in a mixture?
Distillation
Chromatography
Filtration
Centrifugation
What is the main characteristic of a homogeneous mixture?
The components settle over time
The components are visibly different
The components are uniformly distributed
The components can be separated by physical means
Which of the following is an example of a compound?
Saltwater
Oxygen
Sand
Water
Which of the following is an example of a heterogeneous mixture?
Concrete
Vinegar
Milk
Saltwater
What type of mixture is air?
Heterogeneous mixture
Homogeneous mixture
Compound
Pure substance
Which of the following is an example of a pure substance?
Hydrogen
Salt solution
Sand and water
Air
What is a colloid?
A solution in which the solute is in large quantities
A homogeneous mixture with small particles
A heterogeneous mixture with tiny particles
A homogeneous mixture with large particles
What is the key characteristic of a heterogeneous mixture?
Components are uniformly distributed
Components are chemically bonded
Components form a single phase
Components are not uniformly distributed
Which of the following substances is a pure element?
Copper
Sodium chloride
Air
Saltwater
What is the main cause of evaporation?
Decrease in temperature
Increase in pressure
Increase in temperature
Decrease in volume
Which of the following changes is reversible?
Melting of wax
Burning of paper
Rusting of iron
Cooking of food
What is the boiling point of water?
0°C
100°C
50°C
200°C
Which of the following processes involves the change of gas into a liquid?
Evaporation
Freezing
Condensation
Melting
What is plasma?
A solid state of matter
A liquid state of matter
A gaseous state with no particles
A state of matter with charged particles
Which of the following is a property of acids?
Does not change color of litmus paper
Slippery feel
Sour taste
Bitter taste
Which model of the atom is known as the "plum pudding model"?
Dalton's model
Rutherford's model
Bohr's model
Thomson's model
The discovery of the neutron was made by?
Niels Bohr
James Chadwick
Ernest Rutherford
J.J. Thomson
Which part of the atom contains the protons and neutrons?
Nucleus
Electron cloud
Shells
Orbitals