Answer:
B. Atoms in the original substances are arranged in a different way to make new substances.
Explanation:
The best statement that describes a change that occurs in a chemical reaction is that atoms in the original substances are arranged in a different way to make new substances.
- Chemical reactions obey the law of conservation of matter.
- The law postulates that "matter is neither created nor destroyed in a chemical reaction but they are simply rearranged".
- Therefore, atoms of compounds forms new bonds by rearranging to give a new product.
The answer is <span>a total of eight valence electrons
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Answer : The formula for each of the following is:
(a) 
(b) 
(c) 
Explanation :
- Alkanes are hydrocarbon in which the carbon atoms are connected with single covalent bonds.
The general formula of alkanes is 
where n is the number of the carbon atoms present in a molecule of alkane.
- Alkenes are hydrocarbon in which the carbon atoms are connected with double covalent bonds.
The general formula of alkenes is 
where n is the number of the carbon atoms present in a molecule of alkene.
- Alkynes are hydrocarbon in which the carbon atoms are connected with triple covalent bonds.
The general formula of alkynes is 
where n is the number of the carbon atoms present in a molecule of alkyne.
(a) An alkane with 22 carbon atoms
Putting n = 22 in the general formula of alkane, we get the formula of alkane as, 
or
(b) An alkene with 17 carbon atoms
Putting n = 17 in the general formula of alkene, we get the formula of alkene as, 
or
(c) An alkyne with 13 carbon atoms
Putting n = 13 in the general formula of alkyne, we get the formula of alkyne as, 
or
Answer:
2.03 moles of Gold
Explanation:
Gold is one of the most precious metal metal used in many applications and mainly as a jewellery. In terms of purity it is categorized in Karats. 24 Karat is considered the purest Gold (i.e. 100 % Gold) while other Karats (14, 18, 22 e.t.c) are alloys with other metals and gyms.
Data Given:
Mass of Gold = 400 g
A.Mass of Gold = 196.97 g.mol⁻¹
Calculate Moles of Gold as,
Moles = Mass ÷ M.Mass
Putting values,
Moles = 400 g ÷ 196.97 g.mol⁻¹
Moles = 2.03 moles of Gold
The atomic radium increases to the left and downwards on the periodic table.
By that logic, Se has the largest radius.
