Which compound forms double salt with sulphates of alkali metals?

Why is there an increase in the atomic radius of transition elements at the end of the period?

Which of the following metal is used as a thermometric liquid?

Which property of actinoids cannot be explained?

Which isotope of plutonium is used in nuclear bombs?

Which compound is used in Ultra-violet calibration?

Sc3+ is a paramagnetic ion.

What is the first element of the fourth transition series in the periodic table?