Chemistry

Hydroxyapatite is the calcium minerals whose molecular formula is $3C{a}_3{\left(P{O}_4\right)}_2.Ca{\left(OH\right)}_2$ ${}_{}{{}_{}}_{}{}_{}$ or $C{a}_{10}{\left(P{O}_4\right)}_6{\left(OH\right)}_2.$ ${}_{}{{}_{}}_{}{}_{}$ During contact with water dissolved F ion, hydroxyapatite converted into ${}_{}{{}_{}}_{}{}_{}$ $3C{a}_3{\left(P{O}_4\right)}_2.Ca{F}_2$ .

Yellow precipitate is Agl (s) which only produce by structure IV

${?}_0=h{\upsilon }_0$

$=6.6*10^{-34}*1.3*10^{15}J$

^{$=8.58*10^{-19}J$}

During adsorption of a gas on solid surface, process is exothermic i.e. $\Delta H=-ve\left(\Delta H<0\right)$  and entropy decreased, because gas particle resides on solid surface. Hence $\Delta S<0.$

According to Bohr's model, velocity of electron increases according to atomic number (z).

$v_e\propto \frac{z}{n}$ (z = Atomic number and n = number of shell/principal quantum number)

Similarly, velocity of electron decreases according to number of shell (i.e. principal quantum number).

  $\Delta T_f=i*K_f*m$

{for ethylene glycol I = 1, due to non-ionisable}

$=1*1.86*\frac{83*1000}{62*625}K$     

$=3.984K\approx 4K$ (the nearest integer)

Hence, freezing point of solution = 273 K – 4K = 269 K.

$\Delta H_{vap}=41KJmo{l}^{-1}$

$\Delta H=\Delta E+\Delta nRT$      

$H_2{O}_{\left(\mathcal{l}\right)}\to H_2{O}_{vap}$        

$\Delta n=1$             

R = 8.3 JK^-1 mol^-1

T = 373 K

$\Delta$ E (Change of internal energy) = $\Delta H-\Delta nRT$  

$?\Delta E=41-\frac{1*8.3*373}{1000}kJmo{l}^{-1}=41-3.09kJmo{l}^{-1}=37.91kJmo{l}^{-1}$  

Nearest integer = 38.

Kindly consider the following figure

Statement I is true because methyl orange indicator has pH range (3.2 to 4.2) which is suitable for buffer produced by strong acid and weak base.

Statement II is false because phenolphthalein has pH range (8.4 to 10.2) and only suitable for equivalence point above than 7, In this case pH increased by the addition of NaOH on acetic acid.

De-ionised water means dissolved minerals free water which is prepared by synthetic resin method. Where cation exchanged by H⁺ and anion exchanged by OH^- of resin.