Answer: A) grinding coffee beans
Explanation:
A physical change is defined as a change in which there is alteration in shape, size etc. No new substance gets formed in these reactions.
A chemical change is defined as a change in which a change in chemical composition takes place. A new substance is formed in these reactions.
1. Grinding coffee : Only change in size takes place, thus a physical change
2. Baking a cake: the chemical reaction occurs by combination of flour with oxygen , thus a chemical change.
3.:converting water to hydrogen and oxygen: The decomposition iof water takes place, thus is a chemical change
4.Burning of coal: the chemical reaction occurs by combination of carbon with oxygen , thus a chemical change.
Answer:C. The value of n for H+(H2O)n can be calculated for almost all solutions.
Explanation:
An hydrate can be described as a substance that contains water or with an hydrogen bonded water molecule group.
The hydrate group doesn't necessarily have a fixed formula.
Answer:
What is the total number of valence electrons in the Lewis structure of nh4+?
Total valence electrons pairs
Total electron pairs are determined by dividing the number total valence electrons by two. For, NH4+, Total pairs of electrons are 4.
Explanation:
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Answer:
A. SO4 2−
Explanation:
SO₄²⁻
A covalent bond is a bond that forms from sharing of electrons between two atoms. Here, the two atoms combined must have a very low electronegative difference between them, usually 0. Electronegativity deals with the tendency of an atom to attract electrons to itself.
Oxygen and sulfur shows similar tendencies. Since the two atoms shows a strong affinity for their valence electrons in order to complete the octet. This will lead to the eventual sharing of the valence electrons.
