Tag: chemistry

Questions Related to chemistry

Metal cation ionic solids dissolve in solution exothermically.This is best explained by which of the following?

chemistry patterns and properties of metals periodic trends in chemical properties alkali metals study of specific groups

  1. The hydrogen bonding in the water break apart, releasing large amounts of energy that are used to force a breaking of the ionic structure.

  2. The free floating electrons in the metal cations provide a large measure of electricity when the ionic solid is broken down in the water.

  3. The breaking of the ionic structure, which releases bond energy causing the solution to be exothermic.

  4. The attraction of the cations and anions to the dipoles in water, resulting in a release of energy.

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Correct Option: B
Explanation:
Metal cationic  solids dissolve in solution exothermally due the free floating of electrons in the metal cations provide a large measure of electricity when the ionic solid is broken done in the water.

Hence option B is correct.

The reaction between sodium and water can be made less vigorous by:

chemistry patterns and properties of metals periodic trends in chemical properties alkali metals study of specific groups

  1. adding a little alcohol

  2. amalgamatic sodium

  3. adding a little acitic acid

  4. lowering the temperature

Show answer
Correct Option: B
Explanation:

If we add sodium to water it floats on the water and reacts very vigorously, rushing around and on the surface producing hydrogen gas and sodium hydroxide. Hence to reduce its vigorousness, it is amalgamated with mercury by making sodium as amalgamating sodium. 

Option (B) is correct.

Which of the following alkali metal(s) form complex hydrides?

chemistry patterns and properties of metals periodic trends in chemical properties alkali metals study of specific groups

  1. Li

  2. K

  3. Na

  4. Rb

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Correct Option: A,C
Explanation:

Lithium and sodium form complex hydrides such as lithium aluminium hydride and sodium borohydride.

Which of the following reacts most vigorously with water?

chemistry elements of group 1 and group 2 periodic trends in chemical properties alkali metals study of specific groups

  1. Alkali metal

  2. Alkaline earth metal

  3. Transition metal

  4. Halogen

  5. Noble gas

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Correct Option: A
Explanation:

Answer(A)
Alkali metals react most vigorously with water.

Electrical wires have a coating of an insulated material. The material generally used is :

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  1. sulphur

  2. graphite

  3. PVC

  4. None of the above

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Correct Option: C
Explanation:

PVC is an abbreviated form of polyvinyl chloride. The electrical characteristics of PVC such as electrical insulating properties or dielectric constant are excellent and hence, are used as insulating materials.

Which of the following is thermoresistant polymer ?

chemistry man made materials plastic waste thermocol ways to reduce non degradable garbage

  1. Orlon

  2. Polythene

  3. Teflon

  4. Bakelite

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Correct Option: C
Explanation:

Teflon is thermoresistant polymer.


It is also called polytetrafluoroethylene. It is chain growth homopolymer of tetrafluoroethylene $(CF _2=CF _2)$.

$nCF _2=CF _2 \xrightarrow [Polymeriation]{\Delta} (-F _2C-CF _2-) _n$  

State true or false.


Like synthetic fibres, plastic is also a polymer.

chemistry man made materials plastic waste thermocol ways to reduce non degradable garbage

  1. True

  2. False

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Correct Option: A
Explanation:

Plastics are made of very large molecules and hence plastic is a polymer.

The plastics which soften upon being heated but regains all its original properties on cooling are known as:

chemistry man made materials plastic waste thermocol ways to reduce non degradable garbage

  1. thermoplastics

  2. thermosetting plastics

  3. thermoelastic

  4. cellulose

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Correct Option: A
Explanation:

The plastics which soften upon being heated but remain an original properties on cooking are known thermoplastics.

Example: Polythelene, PVC, Acrylic, Nylon and Teflon

Plastic can be used for:

chemistry man made materials plastic waste thermocol ways to reduce non degradable garbage

  1. polythene bags

  2. food packaging

  3. electrical appliances

  4. All of the above

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Correct Option: D
Explanation:

Plastic in today's world plays a very important role in day to day life. They are most commonly used as polythene bags (carry bags). Also they are used in food industry for packaging as wrappers, tetra packs for milk etc. Plastics can be good thermal insulator. Hence, can be used to coat all the electrical appliances.

______ are the substances are capable of molding and casting into various shapes and sizes.

chemistry man made materials plastic waste thermocol ways to reduce non degradable garbage

  1. Thermosettig plastic

  2. Thermoplastic

  3. Polyamide

  4. Polyesters

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Correct Option: B
Explanation:

Thermoplastics are materials which become soft on heating and gets hardened when cooled. This process of heating and cooling can be performed several times on thermoplastic without significant change in its characteristics. Due to these properties, thermoplastics can be molded and cast into various shapes and sizes