7.5 is less accurate then 7.50 because you are getting a less exact measurement.
They expect the Universe to continue expanding. Right now, the evidence is that the expansion is speeding up. They also expect entropy to continue increasing, so in the distant future, there will not be any free energy left to support life, for example.
Answer:
<em>the <u>valency of an element</u> is its combining capacity that is the number of electrons it requires to lose, gain or share in order to become neutral.</em>
[ An element can become neutral if it completes it's octet. That is if an element has 8 electrons in it'd outermost shell then it is considered neutral ]
- The valence of Magnesium is 2 because it requires to lose 2 electrons to become neutral.
- whereas, the valence of Oxygen is 2 because it needs to gain 2 electrons to become stable.
Hence they both have the same valence.
One may say that oxygen's valence is -2 while that of Magnesium is + 2. It's meaning is still the same but "-" sign indicates that oxygen will be gaining electrons in the process of becoming stable.
Explanation:
The electronic configuration of sodium with Z = 11 is : 2, 8, 1
The electronic configuration of chlorine with Z = 17 is : 2, 8, 7
The Lewis structure is drawn in such a way that the octet of each atom is complete.
Thus, sodium losses one electron to chlorine and chlorine accepts this electron to form ionic bond.
Thus, the valence electrons are shown by dots in Lewis structure. The structure is shown in image below.
The correct answer among the choices given is the last option A pH reading of 10 represents a basic solution. pH is a measure of the concentration of hydrogen ions of the substance. Solutions that have more OH– than H+ ions are bases. These are substances that are slippery to touch and has an astringent taste. It reacts with acids in a neutralization reaction forming salts.
