nstse class-12 solution (pcm)

9
website : www.unifiedcouncil.com 1 Mathematics 1. (C) 2 d d (y ) () d d = x x x dy 1 = , d 2y N at (1, 1), m 1 = 1 2 2 d dy ( ) = = 2 , d d x x x x m 2 = 2 tan θ = 1 2 3 2 = 1 4 1 (2) 2 + θ = Tan 1 3 4 . 2. (D) 2 3 5 4 6 9 8 11 15 + + + + + + + + + N N N N N N N N N R 2 R 1 , R 3 R 2 2 3 5 = 2 3 4 4 5 6 + + + N N N 2 1 1 2 C C C C 2 1 2 = 2 1 1 4 1 1 + N = (x + 2) (1 1) 1 (2 4) + 2 (2 4) = 0 + 2 4 = 2. 3. (A) ax 3 + bx is an odd function for all values of a and b. 1 3 1 (a b )d 0 + = x x x for all values of a and b Solutions for Class : 12 (PCM) UNIFIED COUNCIL UNIFIED COUNCIL An ISO 9001: 2008 Certified Organisation NATIONAL LEVEL SCIENCE TALENT SEARCH EXAMINATION Paper Code: UN 415 4. (A) f(5) = Lt 5 N f(x) = Lt 5 N 2 2 10 25 7 10 + + N N N N = Lt 5 N 2 ( 5) 0 ( 2)( 5) = N N N . 5. (A) 2 10 10 A = 02 02 ⎤⎡ ⎥⎢ ⎦⎣ 10 = 04 3 3 2 10 10 10 A = = , 0 2 0 4 0 8 2 0 10 A A = = 2 = 2A 0 4 0 2 ⎤⎡ ⎥⎢ ⎦⎣ 6. (D) a a a Area of triangle = ( ) 1 2a a 2 × = a 2 7. (B) If Sin 1 x = α , Cos 1 x = β then x = sin α , x = cos = β Sin 1 x Cos 1 x = 6 π α β = 6 π sin( α β ) = sin 6 π sin α cos β cos α cos β = 1 2 x 2 (1 x 2 ) = 1 2 2x 2 = 3 2 x = 3 2 .

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Official Answer Key with NSTSE Solutions

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Page 1: NSTSE Class-12 Solution (PCM)

website : www.unifiedcouncil.com

1

=

∴ θ

⎛ ⎞+ ⎜ ⎟⎝ ⎠

⇒ θ

⎛ ⎞⎜ ⎟⎝ ⎠

+ + ++ + ++ + +

+ + +

−−

+

!"##$# %

∴ + =∫ "##$# %

Solutions for Class : 12 (PCM)

A n I S O 9 0 0 1: 2008 C e r t i f i e d O r g a n i s a t i o n

NATIONAL LEVEL SCIENCE TALENT SEARCH EXAMINATION

Paper Code: UN 415

&

&

'

− +− +

&

− =− −

(

− −⎡ ⎤ ⎡ ⎤⎢ ⎥ ⎢ ⎥⎣ ⎦ ⎣ ⎦

⎡ ⎤⎢ ⎥⎣ ⎦

− −⎡ ⎤ ⎡ ⎤ ⎡ ⎤⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎣ ⎦ ⎣ ⎦ ⎣ ⎦

− −⎡ ⎤ ⎡ ⎤− −⎢ ⎥ ⎢ ⎥

⎣ ⎦ ⎣ ⎦

"% ")#% ( )

×

*+α β ,% α

! β

+

π⇒ α β

π

⇒ α β

π

⇒ α !β ! α !β

Page 2: NSTSE Class-12 Solution (PCM)

website : www.unifiedcouncil.com

2

-!. /0

− −⎧ ⎫⎡ ⎤⎛ ⎞⎛ ⎞⎪ ⎪⎢ ⎥⎜ ⎟⎜ ⎟⎨ ⎬⎜ ⎟⎜ ⎟⎢ ⎥+⎝ ⎠⎪ ⎪⎝ ⎠⎣ ⎦⎩ ⎭

−⎧ ⎫⎡ ⎤⎪ ⎪⎨ ⎬⎢ ⎥

+⎪ ⎪⎣ ⎦⎩ ⎭

⎧ ⎫−⎨ ⎬+⎩ ⎭

+

+

+!% ≤ "##∈ 1"%#%2$% %"! ∈ ∉#"$% ≤

≤ 3⇒ ≤ 3 %"! " ≤ ≤ ,%

4%!% 5"# "%"

!θ θ

− θ=θ

67 ,% )%

θ

− θθ ! θ

⇒ θ ! θ

! θ θ !θ θ

! θ θ

67 ,%" #

θ

θθ

! θ

⇒ ! θ θ

! θ θ

! θ

5 #%), ,% 5%"5%! #" " ") ,% )%

θ θ= θ

θ + θ

7 #%), ,% 5%"5%! #" " ") ,%" #

θ= θ

θ + θ

∴57

θ ! θ

'

⎛ ⎞⎜ ⎟−⎜ ⎟⎜ ⎟−⎝ ⎠

) #"

'

−−

8

π

=∫

8

π

=∫

∴ =

⎛ ⎞⎜ ⎟→⎝ ⎠

+→

+→

& !

"

+→

=

= =→

⎡ ⎤⎢ ⎥⎣ ⎦

9

:

: :

⎡ ⎤ ⎡ ⎤⎢ ⎥ ⎢ ⎥− −⎣ ⎦ ⎣ ⎦

⇒ 99 9

⇒ 9

Page 3: NSTSE Class-12 Solution (PCM)

website : www.unifiedcouncil.com

3

⎡ ⎤ ⎡ ⎤− = −⎢ ⎥ ⎢ ⎥⎣ ⎦⎣ ⎦∫ ∫

%

.;,%"% #) /

+ = +

!

⎡ ⎤− +⎢ ⎥⎣ ⎦

⇒ < = =

= −

⎛ ⎞⎜ ⎟⎝ ⎠

⎛ ⎞⎜ ⎟⎝ ⎠

>> α α α α

>>>>>>>>>> α

?$%>>

⇒ α

⇒ α

⇒ α

≤ ./ @

≤ ./

@

≤ @

⇒ ≠

⇒ - ∈ A 0 ∅

! ⇒ !

⇒ !! !

⇒ ! !

⇒ ! !

(

− −⎡ ⎤ ⎡ ⎤⎢ ⎥ ⎢ ⎥⎣ ⎦ ⎣ ⎦

− − − − −⎡ ⎤ ⎡ ⎤⎢ ⎥ ⎢ ⎥−⎣ ⎦ ⎣ ⎦

' '

'

− − −⎡ ⎤ ⎡ ⎤ ⎡ ⎤−⎢ ⎥ ⎢ ⎥ ⎢ ⎥−⎣ ⎦ ⎣ ⎦ ⎣ ⎦

⎡ ⎤ ⎡ ⎤⎢ ⎥ ⎢ ⎥− −⎣ ⎦ ⎣ ⎦

⎡ ⎤⎢ ⎥⎣ ⎦

+ −+ +∫ ∫

⎡ ⎤−⎢ ⎥+ +⎣ ⎦∫

⎡ ⎤ +⎢ ⎥+⎣ ⎦

67 #5"#;,B22α ;,%"% α "%; """ ! +%"%#%7 "%" %)"%%

+ +

)

+ + +

=

+ −+ +

Page 4: NSTSE Class-12 Solution (PCM)

website : www.unifiedcouncil.com

4

C α β 3 γ

3 π

⇒ α β " π ⇒ α β π γ

⇒ α β π γ

α + β− α β

γ

+ = −−

⇒ 3 3⇒ 3 3

∈ ⇒ , ; )%⇒ !

∉ ⇒ "%#%2$%

∈ ∉ ⇒ %"!

∈ ∈

⇒ ∉

4%!% "$%

π

π π

!

!

!

=

⇒ ! !!

⇒ !!!!

⇒ ! !

⇒ !

⇒ !

⇒ !

⇒ !

,% ! A → %%

"% ∈ ,%

5# #%)"%%,#; #% % "%# " !""%5)

∈ !B + ∃ % ∈ !,,4%!%

# ! %! % D5# # !E; D

F

∴ "!#!"%)4%!%%B% #

"% ! G +!% ! "%5%"5%! #"%!,,%";%,$%!

⇒ ⇒ A A, !G"%G%,%"%7 "%$%!"

# 5%

⇒ >>

⇒ →

# 5% !

⇒ !>!>

⇒ →

+#$) ;% )%

∴ G

C 3

=

=

⇒ 3

⎛ ⎞−⎜ ⎟⎝ ⎠

+3

⎛ ⎞− =⎜ ⎟+⎝ ⎠∫ ∫

⇒ 3 #) 3 ! ⇒

#) !

⇒ #) #) !

⇒ % 3!

⇒ !%

H" % !

8

−−

8

− − −+ − =→

Page 5: NSTSE Class-12 Solution (PCM)

website : www.unifiedcouncil.com

5

"%

α =

β !

γ !

α β γ

+ − + −−

α β γ

∴ α β γ α β γ ⇒ α β γ " π

π π π< < ⇒ < < π

⇒ α @β F γ F

⇒ α β γ

%7 "% "%

!

⎛ ⎞⎜ ⎟⎝ ⎠

− = =

∴ = ⇒

⇒ ⇒ "

<

< @

∴ , 2 ;,%

I2 $# %

"% → →

+ );%)%

⇒ "

%7 "% "%

$ % + −∫

⎡ ⎤+ −⎢ ⎥

⎣ ⎦

7

∴ AE → 1 % %

* ! "% ,% % ,% ")#%"%5%!$%# ,%

>> > G &>

+ + = =

>> > G &>

'+ + =

>!> > G &>

'+ + = =

∴ C%" %%"

JJ = J = J = J = =

= J =

JJ JJ

4%"%J × K

µπ × 4

"%), ,% #% K# %" " ,% #%E

,%"%"% %" " 5%" #%), ,% #%

'

Page 6: NSTSE Class-12 Solution (PCM)

website : www.unifiedcouncil.com

6

* * ,% ! ""% ," ), ,% #%

,%J µ *

" *

(

µ

×π× ×

4%"% "× K !,")% α B5"!#%77

× × #

E; Hπ

) )

0

14

× ×−× ×

×

*

E

,; ,% ) "% ,% !%%;%% ,% #%% , # % !

H" %%" ")%

L&; "%!% ×

M

×

Ω

I)%!#%"%)%#,%!#,;%#;, % )%!# 25)," ),,%!##;3%"",% !% ! ""%;## % 3%"

→ − J

+ + # ,

−−

"

J

1

1 ¨

, #,$% % ! %" ,%% "% 5%

H)%"5"5%!%55%"!%%%!%5"#)# "%!%5;%" ,% 55%" ,% #) #"B$#% #),

H × E

−×

−××

×

I)%! %# % #) ! ""%!"") ! !"

% J α

+ !""%! )"5,;## % !

4%"% $× 43

ω ,$ × × ×

× N

−××

%O

JP, D #;

,%"%!%,%,%%"!

- -

. .

" *O

.

- ×

H")%;, βα λ

∴ ββ

λλ

"ββ

λλ µ

1

/

∴ β2 βµ

1

4%"%"%5" !%%"),% ! 5;%", %

CIQ× N

,%"%"%#%%")5" !%%× ×

6C× × × × × × × × N

* L! %5%" )5" !%,%"%7 "% %%") ,%

6 !

" × !

" ×

R

R

× ) )

Page 7: NSTSE Class-12 Solution (PCM)

website : www.unifiedcouncil.com

7

4%"%;$%#%), λ × !

×

O%#! #), ×

* $ ,% "%7 %! ,%

$λ −

××

× 43

× I43

*!%;$%#%),

λ

×

,$Q

$?$%Q" !

Q

9%! %%") 5,%#%!"

$ ,$λ

−× × ×

× N−

−××

%O

C#"% ;##%55%,%;!%;,#% %%") ;,#% #%$),% !#P# 5 J 5#" !,))

* !% "" !

! ""% ) ! B%

!) " ! ! ""%

) ! B% %" !) "

# #;#%,;,#%

#;)"%%" ,

%JJ

J

%,% )%!%#

5" !% ,%5P ,% "),5"J !"! #" 5"J# "),5"#S,%! ""%!"")! !"J#S +!% ,% 5 P #% ,%"),5"J#S

JJ

H ",%" ,% !"! #" %) % J#

%)#% θ ,%5P

J

µ µπ θ×π π π

. .

0 0

. = .4

− × × π

×

4%!%# )%! %# ,%5P

JJJ

J

×

×

,%;" ! #, %O,% ,"%,#;$%#%),

λ

−× − × ××

!

− - "/

-

, ,% "%7 "% 2 ;$%#%),

,%!5!!%#!5!"%5%# ,% )% %"!# !) ",5%3%%5",%% ; ! !"

Q,% 2B" ## % "# %##!#! ,% ,% %G%! %#%!" " #! %! %5$%# !,")%

6%") "%#%%

6 6

J 6

M

× × ×

I%O

# #$%$ % # " α

# #$%$ %

* 5%!% ,% !"! ;## !"%%

,%"%"%" ,%!"! ;##%!"%%

" $%")% 5;%" "% ,%"%!%;##%!"%%

67 $#%"%!%%"% $ #"%!%

* ,% )$% ) "% "%" Ω"% !%!% %"%

Ω Ω

∴ = Ω

,Ω "%"!%!%;,,%

Ω "%"5"##%#,%!%%7 $#%"%!%;

0&

×

&<

⇒ Ω0&

H" P, D #;O *

∴ *

0

Page 8: NSTSE Class-12 Solution (PCM)

website : www.unifiedcouncil.com

8

,% ,; ,% ) "%

∴ θ θ

" θ

" θ

∴ θ

T

#% )%! %5"% " !,#"5%B )%! )%!%5" %,

?% %"!# %" ,; 7 "%5#"!,%"#! 5#%2%

9%%"%#%"%!$%,#%,%

,%" !#%,%%%"%#%"%!$%,,%#5,!#%,%%% +

#4#4PF#4

#P#4

FC,#PC,

** * ***

,% #%! #%CH %25%!% !7 "%

5"# #%!,"!%" %!5"%#%!"" HC;,!, "% # ,% " 5 π π S % ,% "%!%"

,%5"B5""%5 #!"%% )$% ,),%" )#%

S5)+;,C)$%%2"%#%!";,#%5);,#)$%"%,#%

P# % %") 4 " %"%!+!%#4

#PE4#4

% ,%"%"% % %")4 " % "%!

# 4

##

Mg⎯⎯⎯→ # 4

I)J"

⎯⎯⎯⎯⎯→ # 4

#4

#4

PI)J"

J%3%%

,%%7 %!%" !#%% E #%! #%!##%!)" 5,"%% !#%%

#;%" ,% "%%3)5 ;%"

* %%")% B#! %#% %$" #),# " % ,%" %! %;,%;% $% " #% "), ,% !#%"!,")%!"%% ,% % %!"%%)%%!#)% 5,%%; !" % % "#% ,% %%! %!, ,%"

O5 "5"% "%5 "% 1

$ 4)

O5 "5"% "% #

$ 4)

!!") ,% #D #;

$

$

'

,% 2

3

3 // ()

// ()

J#)E% 2);,E4

EP

, 2 "% A "

!##% #

S%! 5 E4 ,% "!%

%#$% 5# 3%" "%" ,),!!%" ""%"#;!!%"

#4

−⎯⎯⎯→

#4

##

,%##;) "

" ! "# %" "% 5#%#4

#4

#4##

* #4

###

#4

**

###4#4

## ***#4

#4###4

##

*O +!% *O , !,"# !",%"%"% , ; 5!# %",%"%"%##$% %""%5#%

J"))D%7

λ θ

× × ×

× × ×

4#PP4 "% !%4)## 4)

##

#4#PP4%

C4)##

)→ C##

4##)

C,5,%

#!,# ,;%2%$%! % %" #%! #" ,")% )6,%" ,; %" #%! #",")%)

1%)#%"BE !# % "5# %"%,#%% 2 "%##

"###

Page 9: NSTSE Class-12 Solution (PCM)

website : www.unifiedcouncil.com

9

#E,%%2"% %"), %"%#P ,% 5%!"!,% !# %"% + ! ! % 2 5#) B"#

4%)%%#95"%%!%E4

!##%")

E## %) # ") ! ")%%,"#%,%"%"%;## "% !, ,% 2 "%

##4

P → 4##4##P

↓4##

)EP##→

*45+,,+

- −

./

012 262'()6 I)→ I)##

4

)

#%##5%#

6%

4+6%

4+

O