Metals are shiny because of their electrons. These electrons produce light when they come in contact with light. I hope this helps.
5.75g
Explanation:
Given parameters:
Number of atoms = 1.505 x 10²³atoms
let us find the number of moles and mass of this atom.
Solution:
The mole is convenient unit for reporting measurements in chemistry. It allows us to make mathematical calculations:
one mole of substance contains 6.02 x 10²³atoms
Number of moles of Na given = 
= 0.25moles
Mass of Na atom given = number of moles x molar mass
Molar mass of Na= 23g/mole
Mass of Na = 0.25 x 23 = 5.75g
learn more:
Number of moles brainly.com/question/1841136
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For 1 mole of S₂O₃²⁻ 0.5 mole of S₂O₈²⁻ will be used.
<h3>What is a balanced Reaction ?</h3>
A reaction in which the number of atoms in reactants is equal to the number of atoms in the products is called a balanced reaction.
The reaction given in the question is
S₂O₈²⁻ + 2I⁻ ⇄ 2SO₄²⁻ + I₂
I₂ + 2S₂O₃²⁻ ⇄ 2I⁻ + S₄O₆²⁻
Adding the equation will give balance equation
S₂O₈²⁻ + 2I⁻ + 2S₂O₃²⁻ ⇄ 2SO₄²⁻ + 2I⁻ + S₄O₆²⁻
So x moles of S₂O₈²⁻ require 2x of S₂O₃²⁻
for 1 mole of S₂O₃²⁻ 0.5 mole of S₂O₈²⁻ will be used.
To know more about Balanced Reaction
brainly.com/question/14280002
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A calorimeter contains 500 g of water at 25°C.....
the temperature of the water inside the calorimeter is 39.4°C.....
The specific heat of water is 4.18 J/g-°C.
energy needed to heat the water = specific heat * mass * temp difference
= 4.18 J/g-°C * 500 g * (39.4°C - 25°C)
= 4.18*500*14.4
= 30096J
or approx. 30kJ
