November 2022 - Page 6 of 10

Which of the following is a substance?

A. Sea water
B. Brass
C. Tape water
D. Graphite
E. Sand

Answer

D. Graphite

All of the listed items, except “Tape water”, are substances. A substance is a material with a fixed chemical composition and defined properties, such as a specific density or melting point.

Sea water is a mixture of salt and water. Brass is an alloy made of copper and zinc. Graphite is a naturally occurring form of carbon. Sand is a naturally occurring mixture of minerals and rock fragments.

“Tape water” is not a substance, but rather a description of water used for taping purposes, such as in construction or repair work.

Which of the following is a substance? Read More »

Some substances are good conductor of electricity in both the solid and liquid states. These substances are generally______________ ?

A. ionic substances
B. metallic substances
C. molecular solids
D. covalent network solids

Answer

B. metallic substances

Metallic substances are good conductors of electricity in both the solid and liquid states. This is because metals have a large number of free electrons in their outermost energy level, which are able to move easily and carry electric current throughout the material. This property makes metals useful in electrical applications, such as wiring and electrical components.

A. Ionic substances are not good conductors of electricity in the solid state, but they can be good conductors in the molten or dissolved state because their ions are free to move and carry electric current.

C. Molecular solids are not good conductors of electricity because their molecules are held together by weak bonds and do not allow for free movement of electrons.

D. Covalent network solids are also not good conductors of electricity because their atoms are bonded covalently, forming a three-dimensional network that does not allow for free movement of electrons.

Some substances are good conductor of electricity in both the solid and liquid states. These substances are generally______________ ? Read More »

What is a mixture of Potassium Nitrate Powdered Charcoal and Sulphur called?

A. Paint
B. Glass
C. Gun Powder
D. Cement

Answer

C. Gun Powder

Gunpowder is a mixture of potassium nitrate (saltpeter), powdered charcoal, and sulfur. This mixture was invented in China over a thousand years ago and was initially used primarily in the manufacture of fireworks. Later, it was adopted for use in weapons, including firearms and cannons, due to its flammability and explosive properties. The burn rate of gunpowder can be controlled by varying the ratios of the three components, making it possible to use it for different purposes such as propelling projectiles or creating a flash and bang for special effects.

What is a mixture of Potassium Nitrate Powdered Charcoal and Sulphur called? Read More »

The diameter of an atom is in the order of________________?

A. 0.2m
B. 0.2mm
C. 0.2nm
D. 0.2pm

Answer

C. 0.2nm

The diameter of an atom is in the order of 0.2 nm (nanometers), which is equivalent to 0.0000002 mm. Atoms are extremely small and cannot be seen with the naked eye. In fact, they are so small that they are measured in nanometers or picometers (1 nm = 10^-9 m, 1 pm = 10^-12 m). The size of an atom is determined by the size of its nucleus, which is much smaller than the electron cloud surrounding it. The electron cloud is what gives an atom its overall size and determines how it interacts with other atoms and molecules.

The diameter of an atom is in the order of________________? Read More »

All of the following substances are crystalline except_____________?

A. Ice
B. Diamond
C. Sucrose
D. Plastic

Answer

D. Plastic

A crystalline substance is one that has a repeating, ordered arrangement of its atoms, molecules, or ions. This arrangement gives rise to a characteristic, repeating pattern of lattice points that can be observed under a microscope. Examples of crystalline substances include ice, diamond, and sucrose (table sugar). Plastic, on the other hand, is an amorphous substance, which means that it lacks a repeating, ordered arrangement of its atoms or molecules. This lack of order gives plastic a random, disordered structure, which can be seen as a lack of regular pattern when viewed under a microscope.

All of the following substances are crystalline except_____________? Read More »

Covalent network crystals have_____________?

A. higher melting point then molecular crystals
B. lower melting point then molecular crystals
C. discrete molecules linked by Van der waals forces
D. hydrogen bonding

Answer

A. higher melting point then molecular crystals

Covalent network crystals are solids in which the atoms are held together by covalent bonds, forming an extensive network of interconnecting bonds. Because of the strong nature of covalent bonds, covalent network crystals tend to have high melting and boiling points compared to other types of solids, such as molecular solids. In comparison, molecular solids are composed of discrete, individual molecules held together by weaker intermolecular forces, such as hydrogen bonding or van der Waals forces. As a result, molecular solids generally have lower melting and boiling points than covalent network crystals.

Covalent network crystals have_____________? Read More »

The radioactive isotope of hydrogen is called___________?

A. tritium
B. deuterium
C. protium
D. ortho-hydrogen

Answer

A. tritium

Tritium is a radioactive isotope of hydrogen. It has the same number of protons as normal hydrogen (1 proton), but it has two neutrons instead of just one, giving it a different atomic weight (3 instead of 1). Tritium is radioactive, which means that it undergoes decay over time and emits high-energy particles. This makes it useful in a number of applications, such as in nuclear weapons and in tritium light sources, which are used to illuminate various devices. However, it also poses some dangers, as tritium can be harmful if it is ingested or inhaled in large quantities.

The radioactive isotope of hydrogen is called___________? Read More »

The soul of chemistry is dealing with___________?

A. Internal structural changes in matter
B. Composition of matter
C. Properties of matter
D. Composition and properties of matter

Answer

D. Composition and properties of matter

Chemistry is a branch of science that deals with the composition, structure, properties, and reactions of matter. The “soul” of chemistry refers to the essence of what makes chemistry so important and interesting. The essence of chemistry is the study of the internal structural changes in matter, its composition, and its properties. This includes understanding the different types of atoms and molecules that make up matter, how they interact with each other, and how they change in response to different conditions, such as heat, pressure, and light. By studying these aspects of matter, chemists can gain insights into the fundamental nature of the world around us, and develop new and useful materials, chemicals, and technologies.

The soul of chemistry is dealing with___________? Read More »