An electron is a negatively charged subatomic particle present in the space outside the nucleus of an atom. The loss of electron from an atom results in the formation of cation whereas gaining of electron by an atom results in the formation of anion. The cation possesses positive charge due to loss of electron and anion possesses negative charge due to gain of electron.
The neutral atom has no charge on it.
For given atomic symbols:
The atomic number of hydrogen is 1 and the given symbol has no charge that means it is in its neutral state. So, the number of electrons in is 1.
The atomic number of helium is 2 and the given symbol has no charge that means it is in its neutral state. So, the number of electrons in is 2.
The atomic number of hydrogen is 1 and the given symbol has a negative charge that represents a gain of electron. So, the number of electrons in is 2.
The atomic number of helium is 2 and the given symbol has two positive charge that represents loss of two electrons. So, the number of electrons in is 0.
Hence, has no electrons.