Which of the following elements is alloyed with copper to form brass?

In the $3d$ series of transition elements,the atomic radius of $Zn$ increases instead of decreasing because...

Determine whether the following statements are True $(T)$ or False $(F)$:
$(a)$ Transition elements exhibit variable oxidation states.
$(b)$ The $E^o$ values for $Mn, Zn,$ and $Ni$ are more positive than expected from the general trend.
$(c)$ Any metal exhibits its maximum high oxidation state in oxide and chloride compounds.

Properties common to the elements manganese,iron,cobalt,nickel,and copper include the ready formation by them all of:
$I$. Coloured ions in aqueous solution
$II$. Oxides of nitrogen are formed on reaction with concentrated $HNO_3$
$III$. Chlorides of formula $MCl_2$ and $MCl_3$

Which of the following pairs of elements in their respective oxidation states develops the same value of calculated spin-only magnetic moment?

Iron loses its magnetic property at: