Answer:
9000 BC
Explanation:
Although various copper tools and decorative items dating back as early as 9000 BCE have been discovered, archaeological evidence suggests that it was the early Mesopotamians who, around 5000 to 6000 years ago, were the first to fully harness the ability to extract and work with copper.
The concentration of HCl is equal to 2.54mol/L.
<h3>Mole calculation</h3>
To solve this question, one must use the molarity calculation, which corresponds to the following expression:
Thus, to find the molarity of the sample, the following calculations must be performed:
So, 0.00254 moles were added per 10ml, so we can do:
So, the concentration of HCl is equal to 2.54mol/L.
Learn more about mole calculation in: brainly.com/question/2845237
Answer:
The correct answer is because they have same number of protons but different number of neutrons.
Explanation:
Isotopes are atoms of the same element but differ only in the number of neutrons in the nucleus, i.e. they have same atomic number but different mass number.
Mass number is affected as they have different number of neutrons, thus effecting their physical properties.
The number of electrons and protons are same, i.e. their atomic number is same and thus their chemical properties are same as chemical properties are determined by the atom’s electronic configuration and that relates to number of protons.
Answer:
D. Surface tension.
Explanation:
Surface tension is defined as the energy required to increase the surface area of a liquid by a unit amount.
The surface tension of a liquid results from an imbalance of intermolecular attractive forces, the cohesive forces between molecules:
A molecule in a liquid experiences cohesive forces with other molecules in all directions while molecules at the surface of a liquid experiences only net inward cohesive forces.
