Answer:-
Neon is a noble gas. Neon with an electronic configuration of 2,8 has 8 electrons in it's outermost shell or valence shell.
According to the Octet theory if an element has eight electrons in it's valence shell then it is stable and does not undergo reaction. Thus Neon does not need to react and can exist freely in nature.
Sodium with an electronic configuration of 2,8,1 has 1 electron in it's valence shell. As per octet rule, it is not stable and it must lose that 1 electron to become stable.
In order to lose that 1 electron sodium must react with other substances. Hence sodium cannot exist freely in nature.
Answer:
Option (b) "174 nm"
Explanation:
Energy of emitted photon is 7.13 eV.
We need to find the wavelength of the photon.
1 eV = 1.6 × 10⁻¹⁹ J
Energy of a photon is given by :
Where, 
is wavelength of the photon
Putting all the values,
So, the wavelength of the photon is 174 nm.
Groundwater adds water to lakes, rivers, and oceans.
ANSWER: D) distributaries
EXPLANATION: When a deposition causes the main channel of a stream to divide into several smaller channel it is called a distributary. They are a common feature of river deltas and is also known as river bifurcation. A distributary generally occurs near a lake or ocean and can also occur near a confluence of large stream. This is popularly also known as arm or channel.
2HNO3 + Ba(OH)2 --> Ba(NO3)2 + 2H2O
Ba(NO3) or barium nitrate is the salt formed
