The lanthanide contraction is responsible for the fact that

Which alga exhibits a haplo-diplontic life cycle?

Which of the following substances is the most acidic?

At $25^{\circ} C$, the concentration of $H ^{+}$ions in $1.00 \times 10^{-3} M$ aqueous solution of a weak monobasic acid having acid dissociation constant $\left(K_a\right)=4.00 \times 10^{-11}$ is $X \times 10^{-7} M$. The value of $X$ is $...$ .
Use: Ionic product of water $\left(K_w\right)=1.00 \times 10^{-14}$ at $25^{\circ} C$

$A$ conducting ring is placed around the core of an electromagnet as shown in the figure. When key $K$ is pressed,the ring