We are asked to convert 25 cg to units of hg.
1 cg = 1 centigram = 10⁻² g
1 hg = 1 hectogram = 10² g
The options given are:
a) 1 hg/ 10² g
b) 10² cg/ 1 hg
c) 10² hg/ 1 cg
d) 10⁻² g/ 1 cg
To convert 25 cg to 1 hg, we could convert the 25 cg to grams first, then grams to hg.
25 cg · 10⁻² g/ 1cg = 0.25 g
Here we have converted our number from cg to grams. We can use another conversion of grams to hg to complete the conversion.
0.25 g · 1 hg/ 10² g = 0.0025 hg
Therefore, the first conversion we used was d) 10⁻² g/ 1 cg.
Answer:
Four electrons are present in the valence shell of Silicon.
Explanation:
Valence shell electrons are those electrons which are present in the outermost shell of an atom. These valence shell electrons are responsible for in the formation of bonds with other atoms.
Silicon having atomic number 14 has fourteen electrons in its neutral state and has the electronic configuration as follow;
1s², 2s², 2p⁶, 3s², 3p²
In given configuration the valence shell (outermost shell) is 3 and the number of electrons present in it are four i.e. 3s² and 3p² (2 + 2 = 4) respectively.
An atom that has 13 protons and 15 neutrons is isotope of Aluminium (answer C)
<u><em>Explanation</em></u>
- Isotope is a form of the same element with the equal number of protons but difference number of neutrons in their nuclei.
- In other words isotope has the same atomic number but different mass number.
- Atomic number of a element is determined by number of protons of an element.
- from the periodic table Aluminum in atomic number 13 therefore it has 13 protons <em>therefore an atom that has 13 protons and 15 neutrons is a isotope of Aluminium. </em>
1.) Na
2.) Cl ( at the second blank)
sodium metal+hydrochloric acid
