Answer is: hydrogen bonds.
Hydrogen bond is an electrostatic attraction between two polar groups that occurs when a hydrogen atom (H), covalently bound to a highly electronegative atom such as flourine (F), oxygen (O) and nitrogen (N) atoms.
According to the principle of base pairing hydrogen bonds could form between adenine and thymine (two hydrogen bonds between this nucleobases) and guanine and cytosine (three hydrogen bonds between this nucleobases).
Adenine and guanine are purine derivatives and thymine and cytosine are pyrimidine derivates.
<u>Answer:</u> The correct option is A) They have fixed energy values.
<u>Explanation:</u>
Electron is one of the sub-atomic particle present around the nucleus of an atom which is negatively charged.
In an atomic model, it is assumed that the electron revolves around the nucleus in discrete orbits having fixed energy levels.
These electrons when jumping from one energy level to another, some amount of radiation is either emitted or absorbed.
These fixed energy levels are given by the Bohr model and thus, the electrons are quantized.
Hence, the correct option is A) They have fixed energy values.
Answer:
b
Explanation:
Plants need carbon dioxide and let out oxygen
Answer:
tanong po sa ipis
Explanation:
because of the gravity of the earth
Answer:

Explanation:
First of all we need to find the amount of atoms per volume (m³). We can do this using the density and the molar mass.

Now, the fraction of vacancies is equal to the N(v)/N ratio.
- N(v) is the number of vacancies

- N is the number of atoms per volume calculated above.
Therefore:
The fraction of vacancies at 600 °C will be:

I hope it helps you!