Tag: chemistry

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Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

D-glucose & D-fructose can be differentiated by :

  1. Fehling solution

  2. Tollens reagent

  3. Benedict test
  4. $Br _2/H _2O$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$Br _2/H _2O$ being a mild oxidising agent can only oxidise aldose to carboxylic acids but cannot oxidise ketose.


As glucose contains aldehyde group it gets oxidised and converted into a carboxylic acid and is differentiate from fructose which has ketone group.

Therefore, the correct option is D.

Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

Free aldehyde group can be produced on hydrolysis of which of the following compound(s)?

  1. Maltose

  2. Sucrose
  3. $\alpha$-D Glucose

  4. Lactose
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Explanation

 $\alpha$-D glucose has cyclic hemiacetal structure. Hemiacetal on hydrolysis gives free aldehyde group.
Maltose, sucrose and lactose are are disacharides which on hydrolysis gives monosaccharides in which aldehyde group becomes free.
Maltose  $\displaystyle \xrightarrow { \text { hydrolysis} }$ Glucose $\displaystyle + $ glucose.
Sucrose  $\displaystyle \xrightarrow { \text { hydrolysis} }$ Glucose $\displaystyle + $ fructose.
Lactose  $\displaystyle \xrightarrow { \text { hydrolysis} }$ Glucose $\displaystyle + $ galactose.

Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

Which of the following is a physical property of sugar?

  1. It is a white crystalline solid.

  2. Carbon, hydrogen, and oxygen are its constituents.
  3. It turns black when concentrated $\displaystyle { H } _{ 2 }{ SO } _{ 4 } $ reacts with it.

  4. When heated it decomposes.

  5. It decomposes readily.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Colour and appearance are physical properties.
The remaining are chemical properties which include its composition, reaction with sulphuric acid and decomposition. 

Multiple choice chemistry metals chemical properties and uses of metals and non-metals introduction to metals physical properties of non-metals

Find the incorrect match.

  1. Fine duct of aluminium - Paints and Lacquers

  2. Reducing agent in the manufacture of dye-stuffs, paints, etc. - copper dust

  3. For cutting tools and crushing machines - Chrome steel

  4. For making cables, automobiles and aeroplane parts - Nickel steel
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The fine duct of aluminium is used in paints and lacquers. For cutting tools and crushing machines chrome steel is used.

For making cables, automobiles and aeroplane part – nickel steel is used. But copper dust is not used as a reducing agent in the manufacture of dyestuffs and paints. So this second is the mismatch.

Correct option is B.

Multiple choice chemistry metals chemical properties and uses of metals and non-metals introduction to metals physical properties of non-metals

Iron is used in construction of bridges and houses.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

There are many different types of steels available today. Each type is made with iron combined with different elements including carbon, silicon, and nickel among others. Steel is an important component in every structure, in every type of construction. Therefore Buildings, bridges, skyscrapers, and other types of construction would not be complete if it does not include iron in its framework. 

Multiple choice chemistry metals chemical properties and uses of metals and non-metals introduction to metals physical properties of non-metals

A fire work gave bright crimson light. It probably contained a salt of ____________.

  1. Ca

  2. Sr

  3. Ba

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

Strontium element gives crimson red flame and it may be the salt of strontium carbonate which is used in the manufacture of red fireworks and pure strontium is used in the study of neurotransmitter release in neurons.