Tag: chemistry

Quizzes (490) Questions (9892)

Questions Related to chemistry

Multiple choice chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

Which is the most active element among folllowing?

  1. Chlorine

  2. Oxygen

  3. Sulfur

  4. Fluorine
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Most active element is Fluorine. The reduction potential of fluorine is very high. Hence, it is extremely reactive in nature. Also F-F bond energy is low (38 kcal/mol). The valence shell electron configuration of fluorine $2s^22p^5$  indicates that it has very strong tendency to take up one electron to attain stable noble gas configuration. Hence, it has high reactivity.

Multiple choice chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

Which of the following is correct?

  1. Iodine is solid

  2. Chlorine is insoluble in water.

  3. Iodine is more reactive than bromine.

  4. Bromine is more reactive than chlorine.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The reason is that the attractive forces between the molecules of these elements increase from top to bottom of the Group.

In iodine, the electrons are so far from the nuclei that the electron clouds can easily distort. The London dispersion forces are strong. So the Iodine is solid.

Hence option A is correct.

Multiple choice chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

Have you ever noticed the fact that two siblings can have different personalities? Even though two people may be members of the same family, it does mean that they will behave in similar ways.
The same thing can be said about elements in a group ("family") on the periodic table. For example, fluorine and iodine are members of the halogen family, but their physical properties are different, as shown in the table below.

Element Melting Point $(^{\circ}C)$ Boiling Point $(^{\circ}C)$
Fluorine $-220$ $-188$
Iodine $+118$ $+184$

Which of the following is the BEST explanation for these differences in melting and boiling point?

  1. Fluorine has a higher value for electronegativity than iodine.

  2. The covalent bond in the fluorine molecule is stronger than the covalent bond in the iodine molecule.

  3. Iodine molecules are larger and more polarizable than fluorine molecules.

  4. Fluorine is a nonpolar molecule, but iodine is a polar molecule.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

As we move down the group of halogens the size of elements increases thereby increasing the Van der Waal forces; hence boiling and melting point of Iodine is more than Fluorine molecule.

Multiple choice chemistry change around us physical changes changes and their classification physical changes

Pick up the correct statement:

  1. Boiling points of alkyl halides are greater than those of the corresponding alkanes.
  2. In water, the solubility decreases as $CH _3OH > C _2H _5OH > C _6H _5OH$.

  3. Aniline is a weaker base than ammonia.

  4. All of the above.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$(A)$  Boiling point $X$ molecular mass of compound hence alkyl halide have greater boiling point

$(B)$  More is the mass of the compound, less is the solubility.
               ${ CH } _{ 3 }OH>{ C } _{ 2 }{ H } _{ 5 }OH>{ C } _{ 6 }{ H } _{ 5 }OH$

$(C)$  Lone pair of aniline in resonance hence a weaker base.
Multiple choice chemistry change around us physical changes changes and their classification physical changes

Physical changes are ________.

  1. Temporary

  2. Permanent

  3. Irreversible

  4. Endothermic
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a physical change, the substances are not altered chemically. No new products are formed. 
A physical change can affect the size, shape or color of a substance but does not affect its composition. The substances may be changed to another phase (i.e. gas, liquid, solid) or separated or combined so physical changes are temporary.

Examples:
when ice melts
when sulfur is mixed with iron filings. 
breaking a glass 
dissolving sugar in water