Answer:
The vertical columns of the periodic table are called groups, or families. The significance is elements with similar properties are placed in the same vertical columns. The horizontal rows of the periodic table are called periods. The significance is that properties vary from left to right along the rows.
Explanation:
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The mass of a NaCl solution that is required to prepare 0.40 L of a 0.75 M solution is 17.55g. Details about mass can be found below.
<h3>How to calculate mass?</h3>
The mass of a substance can be calculated by multiplying the number of moles by its molar mass.
However, the number of moles of a solution must be initially calculated by using the following formula:
molarity = no of moles ÷ volume
no of moles = 0.75 × 0.40
no of moles = 0.3 moles
mass of NaCl = 0.3 × 58.5 = 17.55g
Therefore, the mass of a NaCl solution that is required to prepare 0.40 L of a 0.75 M solution is 17.55g.
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Answer:25,06 kJ of energy must be added to a 75 g block of ice.
ΔHfusion(H₂O) = 6,01 kJ/mol.
T(H₂O) = 0°C.
m(H₂O) = 75 g.
n(H₂O) = m(H₂O) ÷ M(H₂O).
n(H₂O) = 75 g ÷ 18 g/mol.
n(H₂O) = 4,17 mol.
Q = ΔHfusion(H₂O) · n(H₂O)
Q = 6,01 kJ/mol · 4,17 mol
Q = 25,06 kJ.
Explanation: