It involved knots in strings called quipu. The quipu was not a calculator, rather it was a storage device. Remember that the Incas had no written records and so the quipu played a major role in the administration of the Inca empire since it allowed numerical information to be kept.
When you boil water, you aren't changing the elements. You're just making water vapor. However, when you burn paper, it becomes carbon (mostly). So physical changes will not change the substance, only chemical changes will.
4.) D
10.) C
12.) D
13.) D
14.) D
15.) D
Answer:
D) CN⁻
Explanation:
Hund's Rule of Maximum Multiplicity state that electrons go into degenerate orbitals of sub-levels (p,d, and f ) singly before pairing commences. Hund's rule is useful in determining the number of unpaired electrons in an atom. As such, it explains some magnetic properties of elements.
An element whose atoms or molecules contain unpaired electrons is paramagnetic. i.e., weakly attracted to substances in a magnetic field.
On the other hand, the element whose atoms or molecules are filled up with paired electrons is known as diamagnetic, i.e., not attracted by magnetic substances.
According to the molecular orbital theory, the diamagnetic molecule is CN⁻ because of the absence of unpaired electrons.
Answer:
Explanation:
The elements in Group I of the periodic table are called alkali metals. They are called alkali metals because they react with water to form alkali solutions. These metals are very reactive; hence they have to be stored under oil to protect them from corrosion by air and waterwaterwater
