IIT JEE Practice Question and Answer

Q: What has a neck but no head and wears a cap? 1579 0

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Answer :
Explanation :

A bottle has a neck but no head and wears a cap.

Q: Which of the following is the strongest acid? 1578 0

  • 1
    ClCH2COOH
    Correct
    Wrong
  • 2
    BrCH2COOH
    Correct
    Wrong
  • 3
    FCH2COOH
    Correct
    Wrong
  • 4
    ICH2COOH
    Correct
    Wrong
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Answer : 3. "FCH2COOH"
Explanation :

Answer: C) FCH2COOH Explanation: FCH2COOH is the strongest acid out of all .Since the electron withdrawing inductive effect (-I effect) of the halogens decreases in the order   F>Cl> Br> I , therefore the acidic strength of the α- halo acids decreases in the same order.   FCH2COOH  >  ClCH2COOH   >   BrCH2COOH   >   ICH2COOH.

Q: If 2 men and 3 women can do a piece of work in 8 days and 3 men and 2 women in 7 days. In how many days can the work be done by 5 men and 4 women working together? 1578 0

  • 1
    3 days
    Correct
    Wrong
  • 2
    6 days
    Correct
    Wrong
  • 3
    4 days
    Correct
    Wrong
  • 4
    2 days
    Correct
    Wrong
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Answer : 3. "4 days"
Explanation :

Answer: C) 4 days Explanation: From the given data, => (2 M + 3W) 8 = (3M + 2W)7 => 16M + 24W = 21M + 14 W => 10W = 5M => 2W = M => 14W × ? = 7W × 8 ? = 4 days

Q: What is the conjugate base of H2O? 1577 0

  • 1
    NH3+
    Correct
    Wrong
  • 2
    OH-
    Correct
    Wrong
  • 3
    H2O
    Correct
    Wrong
  • 4
    All the above
    Correct
    Wrong
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Answer : 2. "OH-"
Explanation :

Answer: B) OH- Explanation: A conjugate acid, is a species formed by the reception of a proton (H+) by a base—in other words, it is a base with a hydrogen ion added to it. On the other hand, a conjugate base is what is left over after an acid has donated a proton during a chemical reaction. Hence, a conjugate base is a species formed by the removal of a proton from an acid. Because some acids are capable of releasing multiple protons, the conjugate base of an acid may itself be acidic. Represented as the following chemical reaction: Acid + Base ⇌ Conjugate Base + Conjugate Acid   The water molecule is the conjugate acid of the hydroxide ion after the latter received the hydrogen proton donated by ammonium. On the other hand, ammonia is the conjugate base for the acid ammonium after ammonium has donated a hydrogen ion towards the production of the water molecule. We can also refer to OH- as a conjugate base of H2O, since the water molecule donates a proton towards the production of NH+4 in the reverse reaction, which is the predominating process in nature due to the strength of the base NH3 over the hydroxide ion.

Q: At what temperature do pathogenic bacteria grow best in food? 1577 0

  • 1
    5 to 15 degrees Celsius
    Correct
    Wrong
  • 2
    15 to 25 degrees Celsius
    Correct
    Wrong
  • 3
    20 to 45 degrees Celsius
    Correct
    Wrong
  • 4
    40 to 65 degrees Celsius
    Correct
    Wrong
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Answer : 3. "20 to 45 degrees Celsius"
Explanation :

Answer: C) 20 to 45 degrees Celsius Explanation: The Bacteria that causes Food Borne illness are called Food Borne Pathogens. Most of the pathogens are mesophilic in nature, optimum temperature may be around 20-45 degree celsius. This range of temperatures is often called the "Danger Zone." Dry foods do not support the growth of bacteria.   In order to kill pathogenic bacteria you need temperatures above 74ºC. Temperature is the easiest factor to control in order to prevent bacterial growth.

Q: What is the most commonly spoken language in the world? 1577 0

  • 1
    Mandarin Chinese
    Correct
    Wrong
  • 2
    English
    Correct
    Wrong
  • 3
    Spanish
    Correct
    Wrong
  • 4
    Hindi
    Correct
    Wrong
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Answer : 1. "Mandarin Chinese"
Explanation :

Answer: A) Mandarin Chinese Explanation:

Q: Electron configuration of cobalt 2+? 1577 0

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Answer :
Explanation :

The electron configuration for Cobalt at ground state would simply be Co: [Ar] 4s23d7. The s,p,d,f configuration for cobalt (Co) is 1s22s22p63s23p64s23d7 , determined by the position of the element on the periodic table. Cobalt is an inner transition metal which means the electron configuration will end in d block. Cobalt is in the 7th column of the d block and therefore has 7 d electrons d7.

Q: The term biodiversity refers to 1576 0

  • 1
    Range of genetic variation within a population
    Correct
    Wrong
  • 2
    Total number of different species within a habitat
    Correct
    Wrong
  • 3
    Both A & B
    Correct
    Wrong
  • 4
    None of the above
    Correct
    Wrong
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Answer : 3. "Both A & B"
Explanation :

Answer: C) Both A & B Explanation: The term biodiversity refers to the variety of life on Earth at all its levels, from genes to ecosystems, and the ecological and evolutionary processes that sustain it.

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