A. The number of valence electrons increases as atomic mass increases. == Generally true for the representative elements since atomic mass generally increases with increasing Z.
B. The reactivity of alkali metals increases as atomic mass increases. == True. Atomic mass increases down the column and so does reactivity
C. The reactivity of the halogens increases as atomic mass increases. == False. Reactivity decreases down the column.
D. The number of valence electrons decreases across a period. == False. In general, the number of valence electrons increases across a period, particularly for the representative elements.
Answer:
The noble gases are the chemical elements in group 18 of the periodic table. They are the most stable due to having the maximum number of valence electrons their outer shell can hold. Therefore, they rarely react with other elements since they are already stable.Explanation:
Answer:
Explanation:
Blood is an essential part of the circulatory system in the human body. The main function of blood is that it helps to transport materials to different parts of the body where they are need. Blood helps carry waste materials of metabolism from where they are produced to the excretory system. It helps carry oxygen round the body system and it takes out carbon dioxide that is not needed by the body.
Some part of the blood sees to fighting foreign bodies in the system. They are called whiteblood cells. There is no immune system without the white blood cells.
Chloroplasts is an important part in the process of photosynthesis in some organisms. The chloroplast absorbs the energy in sunlight and uses it to produce sugars.
Answer:
Non-zero digits are always significant.
Any zeros between two significant digits are significant.
A final zero or trailing zeros in the decimal portion ONLY are significant. If a number ends in zeros to the right of the decimal point, those zeros are significant.
Explanation:
1.138 has 4 significant figures, which are 1, 1, 3 and 8. The numbers after the decimal point are decimals and are significant figures.
