The correct answer is D:
it involves breaking molecular bonds between copper compounds
.
The explanation :
-when we melt a copper it is a physical change because the substance is still copper and have the same shape.
- but for example Burning a copper it is a chemical change. Fire activates a chemical reaction between copper and oxygen.
-The oxygen in the air reacts with the copper and the chemical bonds are broken.
- the chemical change is changing the other compound bonded to the copper atoms.
So, the correct answer is D
Answer:
Molecules are made of two or more atoms
Molecules are made of atoms of the same element or different elements.
Molecules range in size.
Explanation:
A molecule is formed whenever two or more atoms combine. Hence we can define a molecule as a combination of two or more elements that are combined chemically and can not be separated by any physical means.
Molecules may be composed of the same atoms as in O2, F2 etc or different atoms as in CO2, H2O, etc.
The sizes of molecules differ. Some molecules are quite small in size while others are quite large in size.
Answer:
Pyruvic acid: conjugate base
Lactic acid: conjugate base
Explanation:
The ratio of conjugate base to conjugate acid can be found using the Henderson-Hasselbalch equation when the pH and pKa are known.
pH = pKa + log([A⁻]/[HA])
The equation can be rearranged to solve for the ratio:
pH - pKa = log([A⁻]/[HA])
[A⁻]/[HA] = 10^(pH-pKa)
Now we can calculate the ratio for the pyruvic acid:
[A⁻]/[HA] = 10^(pH-pKa) = 10^(7.4 - 2.50) = 79433
[A⁻] = 79433[HA]
There is a much higher concentration of the conjugate base.
Similarly for lactic acid:
[A⁻]/[HA] = 10^(pH-pKa) = 10^(7.4 - 3.86) = 3467
[A⁻] = 3467[HA]
For lactic acid the conjugate base also dominates at pH 7.4
<span>Mass number is the number of protons and neutrons in an atom, and it tells us about the mass of the atom in amu, or atomic mass units. </span>
<span>Atomic mass is the average mass of all the isotopes of a certain type</span>
With the advancement of science, electrons seemed to possess both particle and wave nature.
this is called the dual nature where electrons have both particle and wave properties.
earlier it was believed that electrons used to orbit around the nucleus in orbits.
Later it was found that electrons do not have fixed positions, the exact momentum and position of electrons cannot be determined at the same time
therefore the wave mechanical model was introduced which introduced orbitals.
Orbitals are spaces in which electrons are most likely to be found. These regions have the highest probability of an electron being found here.
correct answer is 3) an electron
