True.
A catalyst is a substancr that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.
The periodic table is one of the most important tools in the history of chemistry. It describes the atomic properties of every known chemical element in a concise format, including the atomic number, atomic mass and relationships between the elements. Elements with similar chemical properties are arranged in columns in the periodic table.
The table thus is a quick reference as to what elements may behave the same chemically or which may have similar weights or atomic structures.
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iii. True. The existence of a vacancy in a crystal decreases the energy of the material.
One of the scientific disciplines called crystallography examines how the atoms in a solid crystal are arranged. When molecules are linked together in a regular way, these crystals are created.
The mechanical, physical, and optical properties of a material can alter when crystal flaws are present. The strength of the material can be impacted by a flaw.
An irregularity in the atoms' regular geometrical arrangement within a crystalline material is referred to as a crystal defect. These flaws are caused by the solid being deformed, cooling quickly from a high temperature, or being exposed to high-energy radiation (such as X-rays or neutrons). because the vacancy cause defects and the crystal structure is disturbed this causes a decrease in energy.
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Answer:
Speed of light
Explanation:
The value 3.0 x 10⁸m/s is taken as the speed of light.
It is a constant.
- It implies that light travels a distance of 3 x 10⁸ in just one second.
- This value is for the speed of light in a vacuum when there are not particles obstructing its movement.
- The speed of electromagnetic radiations in free space is also taken as the speed of light.
