Which of the following groups of transition metals are known as coinage metals?

Which one of the following statements is $WRONG$ in the context of $X-$rays generated from an $X-$ray tube?

Vapour pressure in $mm \ Hg$ of $0.1 \ mole$ of urea in $180 \ g$ of water at $25^{\circ} C$ is (The vapour pressure of water at $25^{\circ} C$ is $24 \ mm \ Hg$)

The pulleys in the diagram are all smooth and light. The acceleration of $A$ is $a$ upwards and the acceleration of $C$ is $f$ downwards. The acceleration of $B$ is

Cultivation of $Bt$ Cotton has been much in the news. The prefix "$Bt$" means

Coordination compounds have great importance in biological systems. In this context,which of the following statements is incorrect?