Moles = 15.5 g / 40 g/mol = 0.3875 mol
M = 0.3875 mol / 0.250 L = 1.55M
Answer: E. none of these
Explanation: because the f-block element is n-2
Answer: 306 grams are there in 2.50 moles of potassium chlorate
Explanation
According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number
of particles.
To calculate the number of moles, we use the equation:

given mass of potassium chlorate = ?
Molar mass of potassium chlorate = 122.55 g/mol
Putting in the values we get:


306 grams are there in 2.50 moles of potassium chlorate
<h2>Hey There!</h2><h2>_____________________________________</h2><h2>Answer:</h2>

<h2>_____________________________________</h2><h2>CALORIMETER:</h2>
Calorimeter is device used for the measurement of heat. In a calorimeter we can use the temperature change of water to quantify an amount of heat. A calorimeter just captures all the energy released (or absorbed) by a reaction in the water. So Option A and B are wrong as calorimeter don't have anything to do with providing the heat or letting the the heat in, as it is the insulated calorimeter too.
<h2>_____________________________________</h2><h2>Energy in the reaction:</h2>
In the formation of any bond there is equal amount of heat required as to break that bond. It means Energy released in the making of bond is equal to the energy required in the breaking of the bond. So Option D is wrong as it says we need more energy in making then breaking.
<h2>_____________________________________</h2><h2>Enthalpy:</h2>
Enthalpy is the total heat content of the system. As we provide energy to the reactants and the product is formed, so The enthalpy(heat content) of product is more than the Enthalpy of the reactant, Thus Option C is correct.
Enthalpy is denoted by H or Q, its formula is,
H = U + PV
Where,
U is internal energy
PV is equals to Work done ; P = Pressure, V = Volume
<h2>_____________________________________</h2><h2>Best Regards,</h2><h2>'Borz'</h2><h2> </h2>