The valence electrons are the parts of an atom that make interactions and make chemical bonds.
Every atom is made of three different components, a positively charged proton, neutrally charged neutron and negatively charged electron. The protons and the neutrons make up the atom's core and the electrons orbit around that core.
The electrons that orbit around the atom's core in its outer-most orbit (the one that is the furthest from the atom's core) can interact with electrons of other atoms, forming different kinds of chemical bonds.
If there is an exchange of the electrons (one atom donates its electrons to another atom), that results in forming of ions, then those two atoms can be linked in an ionic bond.
If an electron is shared between two atoms, then that bond is called a covalent bond.
First, they may produce direct and relatively short-lived effects, such as stimulation of the isolated uterus or relaxation of the isolated tracheal chain preparation.
Secondly, in doses too low to produce a direct effect, they may produce a long-term potentiation of the effects of other stimulants.
Answer:
B. flourine
Flourine is the 9th element in the periodic table
Answer:

Explanation:
A protein is a long chain of amino acids linked together by amide groups.
The general structure is
![\rm \left[-NHCHR-\underbrace{\hbox{CO-NH}}_{\hbox{amide group}}-CHRCO-\right]_{n}](https://tex.z-dn.net/?f=%5Crm%20%5Cleft%5B-NHCHR-%5Cunderbrace%7B%5Chbox%7BCO-NH%7D%7D_%7B%5Chbox%7Bamide%20group%7D%7D-CHRCO-%5Cright%5D_%7Bn%7D)
Answer:
1- 0.04 M/s.
2- 0.16 M/s.
Explanation:
- For the reaction: 4PH₃ → P₄ + 6H₂.
<em>The rate of the reaction = - d[PH₃]/4dt = d[P₄]/dt = d[H₂]/6dt.</em>
where, - d[PH₃]/dt is the rate of PH₃ changing "rate of disappearance of PH₃".
d[P₄]/dt is rate of P₄ changing "rate of appearance of P₄".
d[H₂]/dt is the rate of H₂ changing "rate of formation of H₂" (d[H₂]/dt = 0.24 M/s).
<u><em>(a) At what rate is P₄ changing?</em></u>
∵ The rate of the reaction = d[P₄]/dt = d[H₂]/6dt.
∴ <em>rate of P₄ changing = </em>d[P₄]/dt = d[H₂]/6dt = (0.240 M/s)/(6.0) = 0.04 M/s.
<u><em>(b) At what rate is PH</em></u>₃<u><em> changing?</em></u>
∵ The rate of the reaction = - d[PH₃]/4dt = d[H₂]/6dt.
∴ <em>rate of PH</em>₃<em> changing = </em>- d[PH₃]/dt = 4(d[H₂]/6dt) = (4)(0.240 M/s)/(6.0) = 0.16 M/s.