Tag: chemistry

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Questions Related to chemistry

Multiple choice chemistry classification of elements- the periodic table introduction to periodic table necessity of classification need for classification

The elements posses stable electronic configuration are called as __________.

  1. Transition metals

  2. Non-transition metals

  3. Noble gases

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Noble gases have stable configuration of $ns^2 np^6$ with their octet completely filled which, gives them stability. Helium has exception.

Multiple choice chemistry classification of elements- the periodic table introduction to periodic table necessity of classification need for classification

According to classification of elements most of non-metals are placed in ________ block.

  1. $s$ - block
  2. $p$ - block
  3. $d$ - block
  4. $f$ - block
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The $p$ - block is the area of the periodic table containing columns $3A$ to column $8A$ (columns$ 13-18$), including noble gas, all non metals, metals and metalloids. 

Multiple choice chemistry classification of elements- the periodic table introduction to periodic table necessity of classification need for classification

After the classification of elements study of elements become____________.

  1. difficult

  2. easy

  3. both A and B

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

 Elements with similar chemical properties generally fall into the same group in the periodic table, and the elements in the same period tend to have similar properties.Thus, it is relatively easy to predict the chemical properties of an element if one knows the properties of the elements around it.

Multiple choice chemistry classification of elements- the periodic table introduction to periodic table necessity of classification need for classification

Classification of elements are done on the basis of ___________.

  1. atomic number

  2. atomic weight

  3. valency

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Based on the modern periodic law, the elements are arranged into rows and columns based on their atomic number. There are 18 columns, called groups and 7 rows, called periods. 

Multiple choice chemistry classification of elements- the periodic table introduction to periodic table necessity of classification need for classification

The physical properties of elements changes according to_____________.

  1. classification of elements in groups and periods

  2. classification of elements in groups

  3. classification of elements in periods

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The physical properties (notably, melting and boiling points) of the elements in a given trend in vary from group to group and from period to period.


Hence the correct option is A.

Multiple choice chemistry atomic theory, periodic classification and properties of elements introduction to periodic table necessity of classification need for classification

Catalyst in a reaction:

  1. lower the activation energy

  2. increases the activation energy

  3. increases the rate of reaction

  4. both A and C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A catalyst increases the rate of a reaction by providing an alternative pathway with a lower activation energy. Since both statements A and C are correct, D is the correct choice.

Multiple choice chemistry atomic theory, periodic classification and properties of elements introduction to periodic table necessity of classification need for classification

A biological catalyst is

  1. $N _2$ molecules

  2. an enzyme

  3. an amino acid<span class="MathJax MathJax_Processing">

  4. a carbohydrate
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Biological catalysts are proteins known as enzymes, which speed up biochemical reactions in living organisms. Amino acids are the building blocks of enzymes, but the enzyme itself is the catalyst.

Multiple choice chemistry atomic theory, periodic classification and properties of elements introduction to periodic table necessity of classification need for classification

Transition elements are also known as ____________.

  1. $d$ - block elements
  2. $f$ - block elements
  3. $s$ - block elements

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The transition elements are also known as the $d$-block elements because while the outermost level contains at most two electrons, their next to outermost main levels have incompletely filled $d$ sub-orbitals, which are filled-up progressively ongoing across the periodic table from $8$ to $18$ electrons. The filling of the $d$ sub-orbitals of the transition elements across a row of the periodic table is not always regular.


Hence, the correct option is $\text{A}$

Multiple choice chemistry atomic theory, periodic classification and properties of elements introduction to periodic table necessity of classification need for classification

A metal crystallizes with a face-centred cubic lattice. The edge length of the unit cell is 408 pm. The diameter of the metal atom is:

  1. 228 pm

  2. 288 pm

  3. 144 pm

  4. 326 pm
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In a face-centered cubic (FCC) lattice, the relation between edge length (a) and atomic radius (r) is a = 2 * sqrt(2) * r. The diameter (d) is 2r. Thus, d = a / sqrt(2). Given a = 408 pm, d = 408 / 1.414 = 288.5 pm, which rounds to 288 pm.