18. Which one of the following is generally NOT true about elements in the same period?
A. Number of valence electrons of the elements remains the same.
B. Elements at the right side of the period are smaller in size
C. Elements at the right side of the period have higher electron affinity.
D. Elements at the right side of the period have high metallic character.

Statement B "Elements at the right side of the period are smaller in size" is not true.

Explanation:

Going through the rows of the elements in the period the size of the elements get continuously bigger.

answer: the value of enthalpy change will be -152.80 kj.

solution:

pressure = 1atm , temperature = = 298 k

given that pressure and temperature are same in both gases , the number of moles of both gases can be determined by the ideal gas equation.

according to reaction 3 moles no are reacting with 1 mol of ,then 0.49 mol of no will react with moles of ozone that is 0.16 moles of ozone. since, no is limiting reagent and is an excessive reagent.

enthalpy change for the reaction between the given volumes of the gases is :

what does the table look like