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Need for classification - class-IX

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In laboratory burners, we use

  1. Producer gas

  2. Oil gas

  3. Gobar Gas

  4. None of the above


Correct Option: B
Explanation:

In laboratory burners , oil gas is generally used oil gas is mixture of $CH _4 + CO + CO _2 + H _2$

Hence, the correct option is B

Who was the first to classify the elements into metals and non-metals?

  1. Meyer

  2. Mendeleev

  3. Lavoisier

  4. None of the above


Correct Option: C
Explanation:

Lavioser was the first person to classify elements into metals and non metal. The concept of metalloids came in later

The elements posses stable electronic configuration are called as __________.

  1. Transition metals

  2. Non-transition metals

  3. Noble gases

  4. None of these


Correct Option: C
Explanation:

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

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


Correct Option: B
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. 

After the classification of elements study of elements become____________.

  1. difficult

  2. easy

  3. both A and B

  4. None of these


Correct Option: B
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.

Classification of elements are done on the basis of ___________.

  1. atomic number

  2. atomic weight

  3. valency

  4. none of these


Correct Option: A
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

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


Correct Option: A
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.

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


Correct Option: D

Transition elements are also known as ____________.

  1. $d$ - block elements

  2. $f$ - block elements

  3. $s$ - block elements

  4. None of these


Correct Option: A
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 $\text{A}$

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


Correct Option: B

Hydrolysis of urea is an example of

  1. Homogenious reaction

  2. heterogenious reaction

  3. Biomolecular reaction

  4. Both a and b


Correct Option: C
Explanation:

Enzymes are biological catalysts which catalyze the biochemical reactions in living organisms.

Hydrolysis of urea by urease is an example of  biochemical catalysis.

 

Predict block, group and period of $Sb$.

  1. Block-$p$, Period-$5$, Group-$15$

  2. Block-$p$, Period-$5$, Group-$14$

  3. Block-$s$, Period-$5$, Group-$13$

  4. Block-$s$, Period-$5$, Group-$11$


Correct Option: A
Explanation:

Antimony is a chemical element with symbol $Sb$ (from Latin: stibium) and atomic number $51$,group $15$ (pnictogens), $p$-block,period $5$.

Based on modern classification of periodic table atomic number increases on moving from _________ in periodic table.

  1. left to right

  2. right to left

  3. straight

  4. none of these


Correct Option: A
Explanation:

Elements in the same period tend to have shared chemistry and exhibit a  trend in properties with increasing atomic number from left to right.

The modern periodic table is most_________ form of periodic table.

  1. insignificant

  2. Significant

  3. Both A and B

  4. None of these


Correct Option: B
Explanation:

In the standard periodic table, the elements are listed in order of increasing atomic number. Thus, it is relatively easy to predict the chemical properties of an element if one knows the properties of the elements around it i.e. it is more significant form of periodic table.

Significance of classification of periodic table is to ___________.

  1. predict the blocks of elements

  2. predicts the groups of elements

  3. both A and B

  4. none of these


Correct Option: C
Explanation:

Periodic classification of elements is the method by which elements are grouped on the basis of their characteristics. Classification of elements in groups provide us a fixed pattern in which the elements change their properties periodically. Periodic table made the study of physical and chemical properties of elements simple and organized.

Classification of periodic table based on atomic number is given by:

  1. Mendeleev's

  2. Mosley

  3. Both A and B

  4. None of these


Correct Option: B
Explanation:

Henry Moseley found a relationship between the X-ray wavelength of an element and its atomic number. Moseley's discovery showed that atomic numbers were in fact based upon experimental measurements.

Alkali and alkaline earth metals are ________ elements.

  1. same

  2. different

  3. both A and B

  4. none of these


Correct Option: B
Explanation:

Alkali and alkaline earth metals are group I and group II elements of s block representative elements with ns$^1$ and ns$^2$ valence shell configuration respectively.


Hence, option B is correct.

Lanthanoids are also called as ___________.

  1. Transition elements

  2. Rare earth elements

  3. Both A and B

  4. None of these


Correct Option: B
Explanation:

Rare earth metals are a group of chemically similar metallic elements comprising the lanthanide series and (usually) scandium and yttrium. They are not especially rare, but they tend to occur together in nature and are difficult to separate from one another.

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