MCQ
An ion which has $18$ electrons in the outermost shell is
- A${K^ + }$
- B$C{s^{ + }}$
- C$T{h^ 4+ }$
- ✓$C{u^ + }$
$Cu (29)=2,8,18,1$
$C u^{+}=2,8,18$
$\operatorname{Th}(90)=2,8,18,32,18,10,2$
$T h^{4+}=2,8,18,32,18,8$
$\operatorname{Cs}(55)=2,8,18,18,8,1$
$C s^{+}=2,8,18,18,8$
$K (19)=2,8,8,1$
$K^{+}=2,8,8$
Thus, $C u^{+}$has $18$ electrons in the outermost shell.
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${N_2}{O_4}(g)\, \to \,2N{O_2}(g)$
Data for the given reaction is
$\Delta H = +54\,kJ$ and $E_a = + 57.2\,kJ$
.......$kJ$
Assertion $A$: In the photoelectric effect, the electrons are ejected from the metal surface as soon as the beam of light of frequency greater than threshold frequency strikes the surface.
Reason $R$ : When the photon of any energy strikes an electron in the atom, transfer of energy from the photon to the electron takes place.
In the light of the above statements, choose the most appropriate answer from the options given below :
if one mole of each of $X$ and $Y$ with $0.05 mol$ of $Z$ gives compound $XYZ _{3}$. (Given : Atomic masses of $X , Y$ and $Z$ are 10,20 and $30 amu$, respectively). The yield of $XYZ _{3}$ is $.........g$.(Nearest integer)