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Chemical formula

Example: Balanced Chemical Equations with Subscripts Water: $$\ce{H2O}$$ Carbon dioxide: $$\ce{CO2}$$ Iron(III) hydroxide (Rust reaction): $$\ce{4Fe + 3O2 + 6H2O -> 4Fe(OH)3}$$ Copper(II) sulfate pentahydrate: $$\ce{CuSO4 * 5H2O}$$ Chemical Formulas in Chemistry Chemical formulas are the symbolic representations of chemical substances. They show the elements present in a compound and the ratio in which the atoms of these elements combine. Chemical formulas are essential for understanding the composition, structure, and behavior of compounds in chemical reactions. 1. What is a Chemical Formula? A chemical formula uses symbols of elements and numerical subscripts to represent the composition of a substance. For example, the formula for water is: $$ \ce{H2O} $$ This indicates that each water molecule is made up of 2 atoms of hydrogen and 1 atom of oxygen. 2. Types of Chemical Formulas Empirical Formula Molecular Formula Structural Formula...
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IIT MCQ

1. If a ,b , c are non zero real numbers and az^2 + bz + c + I = 0 has purely imaginary roots , then a equals 
 
  (a) bc
  (b) b^2c 
  (c) -b^2c 
  (d) 1/2b^2c 

Answer: (b) 

2. 'A' is an organic compound which can reduce Tollen's reagent , reduces mercuric chloride giving black precipitate, decolourises acidified KMnO4 and can reduce Fehling solution also. Compound 'A' is : 

 (a) Formic acid 
 (b) Ethyne 
 (c) Ethanal 
 (d) Ethene 

Answer: (a) 

3. A photosensitive metallic surface has work function hVo . If the photons of energy 2hVo falls on this surface , the electrons come out with a maximum velocity of 4 x 10^6 m/s . When the photon energy is increased to 5hVo , then maximum velocity of photoelectrons will be : 

 (a) 2 x 10^6 m/s 
 (b) 2 x 10^7 m/s
 (c) 8 x 10^7 m/s
 (d) 8 x 10^6 m/s 

Answer:  (d) 

4. Auto oxidation of bleaching powder gives 

 (a) only calcium chlorate 
 (b) only calcium chloride 
 (c) only calcium hypochlorite 
 (d) Both (a) and (b) 

Answer: (d) 

5. Two unit vectors when added give a unit vector. Then choose the correct statement : 

 (a) Magnitude of their difference is √3
 (b) Magnitude of their difference is 1 
 (c) Angle between the vectors is 90° 
 (d) Angle between the sum and the difference of the two vectors is 60° 

Answer: (a) 

6. The wavelength of the Ka line for the uranium atom (z = 92 ) is ( R = 10^7 m^-1 ) : 

 (a) 1.6 A°
 (b) 0.16 A° 
 (c) 0.5 A° 
 (d) 2.0 A° 

Answer: (b) 

7. f(x) = x^3 + sinx is an even function 
 
 (a) True 
 (b) False 

Answer: (b) 

8. The disease albinism is caused by the deficiency of enzyme : 

 (a) Trypsin 
 (b) Tyrosinase 
 (c) Phenylalanine hydroxylase 
 (d) None of these 

Answer: (b) 

9. A particle executes simple motion between x = -A and x = +A . The time taken for it to move from x = 0 to x = A/2 is T1 and to move from x = A/2 to x = A/√2  is T2 . Then 

(a) T1 < T2
(b) T1 = T2 
(c) T1 = 2T2 
(d) T2 = 2T1 

Answer: (c) 

10. If f(x)g(x) and f(x)  are continuous at x= a then g(x) is continuous at x = a 

 (a) True 
 (b) False 

Answer: (b) 

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