Can someone help with this I don’t get it???

For this specific star, it would be magnesium

Explanation:

when you look at the spectrum of light for, in this case, a star, you are seeing a specific light signature, like a fingerprint. you have to compare the black lines of the star's light spectrum to the light spectrum of different gasses to see which ones match up. in this case, the lines in star 8's spectrum match the lines in the spectrum of magnesium.

option a is correct i.e.

explanation:

in context to the membrane of nerve impulse, the outer membrane of neuron is semi permeable that is only sodium ions can pass through the membrane i.e. smaller ions can pass through the membrane while larger ions cannot pass through it.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products