Answer:
1. hydrogen - H
2. helium - He
3. sodium - Na
4. magnesium - Mg
5. potassium - K
Explanation:
Hydrogen is the element of group 1 and first period. The atomic number of hydrogen is 1 and the symbol of the element is H.
The electronic configuration of the element hydrogen is:-

Helium is the element of group 18 and first period. The atomic number of helium is 2 and the symbol of the element is He.
The electronic configuration of the element helium is:-

Sodium is the element of group 1 and third period. The atomic number of sodium is 11 and the symbol of the element is Na.
The electronic configuration of the element sodium is:-

Magnesium is the element of group 2 and third period. The atomic number of magnesium is 12 and the symbol of the element is Mg.
The electronic configuration of the element magnesium is:-

Potassium is the element of group 1 and forth period. The atomic number of potassium is 19 and the symbol of the element is K.
The electronic configuration of the element potassium is:-

Answer: Hope this helps
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Explanation: <u><em>
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Answer:
C2H5OH is a formula of ethyl alchol or ethanol.
alkenes are characterisized by carbon-carbon double bond.
burning is an example of exothermic reaction
atomic number of element is x the symbol of its ion is +1 bcz it will lose one electron
if temperature increases then rate of chemical reaction increases
Explanation:
i hope this will help you :)
An open system is
when there is a transfer of energy and matter with its surroundings.
A closed system is
where there is a transfer of energy, may it be heat or work, but not matter
with its surroundings.
An isolated system
is where there is no transfer of energy or matter with its surroundings.
For a given peak intensity of radiation of a star that occurs at a wavelength of 2 nanometers, this is located at the spectral band of an X-ray. An X-ray's wavelength typically goes from 0.1 nano meters to 10 nano meters. Given that, the wavelength of the star fits perfectly into the range of an X-ray