Answer:
The atomic number of the isotope is reduced by 2 and atomic mass is reduced by 4.
Explanation:
Alpha particle is doubly ionized helium atom. The atomic mass of helium atom is 4 u and atomic number of helium atom is 2. The emission of alpha particle means doubly ionized helium atom will be released from the isotope.
Hence, the emission of the alpha particle will decrease the atomic mass by 4 and atomic number by 2.
Hence, option(a) is correct
Answer:
Explanation:
To convert from moles to grams, the molar mass must be used.
1. Find Molar Mass
The compound is sodium sulfide: Na₂S
First, find the molar masses of the individual elements in the compound: sodium (Na) and sulfur (S).
- Na: 22.9897693 g/mol
- S: 32.07 g/mol
There are 2 atoms of sodium, denoted by the subscript after Na. Multiply the molar mass of sodium by 2 and add sulfur's molar mass.
- Na₂S: 2(22.9897693 g/mol)+(32.07 g/mol)=78.0495386 g/mol
This number tells us the grams of sodium sulfide in 1 mole.
2. Calculate Grams
Use the number as a ratio.
Multiply by the given number of moles, 3.46.
The moles of sodium sulfide will cancel.
3. Round
The original measurement of grams, 3.46, has 3 significant figures. We must round our answer to 3 sig figs.
For the answer we calculated, that is the ones place.
The 0 in the tenth place tells us to leave the 0 in the ones place.
There are about <u>270 grams of sodium sulfide</u> in 3.46 moles.
Answer:
B
Explanation:
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Answer:
2.1mol/L
Explanation:
Number of moles = 0.21 moles
Volume = 0.1L
Molarity of a substance is the number of moles of solute dissolved in a volume of solvent (L)
Molarity = number of moles / volume of solvent
Molarity = 0.21 / 0.1
Molarity = 2.1mol/L