214 - Chemistry Questions Answers

what is the relation b/w E1 &E2 whose respective wavelength r 400& 800 Ao . SIR I WANT TO KNOW THE RELATn b/w ENERGY & WAVELENGTH . ARE THEY DIRECTLY PROPTIONAL  ? ANS OF THIS QUES IS E1=2E2

Asked By: SARIKA SHARMA
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Joshi sir comment

E = hc/λ

so E is inversely proportional to λ 

THE FIRST EMISSION LINE IN THE ATOMIC SPECTRUM OF HYDROGEN IN BALMER SERIES APPEAR AT ?

ANS 5R/36cm-1

Asked By: SARIKA SHARMA
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Joshi sir comment

for balmer series of hydrogen atom 

 1/λ = R ( 1/22  -   1/32)     

solve for λ

IF n & l are principle & azimuthal quantum no. respectively then expression for calculating total no. of e- in any energy level is?

summation from l=0 to n-1 (2(2l+1)) HOW

Asked By: SARIKA SHARMA
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Joshi sir comment

for nth level values of l will be 0, 1,  2,  3, 4, 5, .....................(n-1) 

for l = 0   means s subshell no. of electrons = 2      = 2(2*0+1) 

for l = 1 means p subshell no. of electrons = 6        = 2(2*1+1)

for l = 2 means d subshell no. of electrons = 10      = 2(2*2+1)

similarly for others 

 

0.2 g OF SAMPLE OF H2O2  REQUIRED 10ml OF 1N KMnO4 SOLn  IN A TITRATION IN +NCE OF dil H2SO4 . THE % PURITY OF H2O2 IS?

ANS 85

 

Asked By: SARIKA SHARMA
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Joshi sir comment

No. of gm. equivalent of KMnO4 = No. of gm. equivalent of H2O2

so 1*10/1000   =     x  /  17             (17 is eq. wt. of H2O2

so  x = 0.17

so % purity = 0.17*100/0.2 = 85 

HOW MUCH WATER IS TO BE ADDED TO DILUTE 10ml OF 10N HCl TO MAKE IT DECINORMAL ?

ANS 100ml

Asked By: SARIKA SHARMA
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Joshi sir comment

N1V1 = N2V2

so 10*10 = 0.1*v 

or v = 1000 ml

so extra water added will be 990 ml

 

the normality of 10% (w/v) acetic acid is ?

1.7N

Asked By: SARIKA SHARMA
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Joshi sir comment

10 % w/v acetic acid means 10 gm. in 100 ml. soln.

so 1000 ml soln. contains 100 gm acetic acid

so 1 litre contains 100/60 moles of acetic acid

so M = 100/60 = 1.67

so N = M * basicity = 1.67*1 = 1.67 

the ques which i have already submitted i.e. d ques in which we have to find min transitional energy in terms ofRH , IS THE ANS IS RH. PLS AGAIN TELL THAT SOLn so that i can understand more easily

Asked By: SARIKA SHARMA
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Joshi sir comment

for max transitional energy we will use 

E = hcRH {1/12  - 1/∞2}

so E will be proportional to RH

oxide of E react with KOH & give compd like KMnO4 WHAT IS THE FORMULA OF OXIDE OF E

EO

E2O3

E2O7      OR ANY OTHER ANS (& IF ANY OTHER ONE THEN GIVE THAT ANS WITH SOLn)

 

Asked By: SARIKA SHARMA
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Joshi sir comment

 

2 EO2 + 4 KOH + O2 → 2 K2EO4 + 2 H2O
and
3 K2EO4 + 2 CO2 → 2 KEO4 + 2 K2CO3 + EO2
 
so oxide will be EO2
 
 
 

IF D POSITn OF Na+ & Cl - rR INTERCHANGED IN NaCl having FCC ARRANGEMENT OF Cl- THEN IN D UNIT CELL OF NaCl

Na + WILL INCREASE  BY 1 WHILE Cl- DECREASE BY 1

PLS TELL D REASON

Asked By: SARIKA
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Joshi sir comment

No, 

These will be no change by making this type of change

THE PYKNOMETRIC DENSITY OF NaClis 2.165X 10-3 wHILE ITS Xray density  IS 2.178X103 kgm-3 the fraction of unoccupied sites in NaCl crystal is?ans) 5.96x 10-3.   how we will caculate this fraction

Asked By: SARIKA
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Joshi sir comment

Pyknometer is a device to measure density of substance. Density measured by pyknometer is called pyknometric density. In porous solids this density may be different from true density of solid if the liquid used is unable to fill the pores of solid.

I think that the first density will be 2.165 * 103

difference of density = 2178-2165 = 13 kg/m3

so fraction of unoccupied site = 13/2178 =  5.96 * 10-3

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