Tag: changes and their classification

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

Boiling water is a _____ change because _____.

  1. Physical, the gaseous water produced is chemically identical to the liquid water the process began with

  2. Physical, the water was disappeared

  3. Chemical, heat was required for the change

  4. Chemical, the process produced a gas
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Boiling water is a physical change because the gaseous water produced is chemically identical to the liquid water i.e both of them have the same molecular structure of the water.

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

According to the CRC's  the melting point of cadmium bromide is $868^{\circ}C$. Which of the following equations best describes what occurs when cadmium is heated to $868^{\circ}C$?

  1. $CdBr(s)\rightarrow CdBr(l)$
  2. $CdBr _{2}(s)\rightarrow CdBr _{2}(l)$
  3. $CdBr _{2}(s)\rightarrow Cd(s) + Br _{2}(g)$
  4. $CdBr _{2}(s)\rightarrow Cd^{2+}(aq) + 2Br^{-}(aq)$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Heating a solid substance to its melting point causes a phase transition from the solid state to the liquid state without chemical decomposition. Therefore, solid cadmium bromide transforms into liquid cadmium bromide at 868 degrees Celsius.

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

What kind of changes is undergone when an electric bulb glows?

  1. A physical change

  2. A chemical change

  3. Both a physical and a chemical change

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

When an electric bulb glows a physical change is observed. As the light produced by the electric bulb is due to the heating effect of the conductor. Even though there is an occurrence of temperature change since no new substances are produced it is considered to be a physical change.

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

Your lab partner mixed two colorless solutions in the test tube. He sees no observable changes in the resulting mixture and is unable to detect any change in temperature. Based on these observations, what type of reaction has taken place?

  1. A physical reaction

  2. A chemical reaction

  3. An exothermic reaction

  4. An endothermic Reaction
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When two solutions are mixed and no observable changes like evolution of gas or precipitate formation takes place then the reaction is reversible and the reaction is a physical reaction.

Ans :- A

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

The melting point of cadmium bromide is $568^{\circ}C$. Which of the following equations best describes what occurs when cadmium bromide is heated to $568^{\circ}C$?

  1. $CdBr(s)\rightarrow CdBr(l)$
  2. $CdBr _{2}(s)\rightarrow CdBr _{2}(l)$
  3. $CdBr _{2}(s)\rightarrow Cd(s) + Br _{2}(g)$
  4. $CdBr _{2}(s) \rightarrow Cd^{2+} (aq) + 2Br^{-}(aq)$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Melting point is defined as the temperature at which solid is converted to liquid.

Given, Melting point of $Cd{ Br } _{ 2 }={ 568 }^{ 0 }C$

So, At ${ 568 }^{ 0 }C$

${ CdBr } _{ 2 }\left( solid \right) \longrightarrow { CdBr } _{ 2 }\left( liquid \right) $
Ans :- A

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

Adam traveled from his home in New York down to Florida for summer vacation. So you say that Adam experienced both a change in temperature and a change of state! When we study states of matter in chemistry, it is important to focus on atoms (not Adam).
Which of the following BEST describes the differences between atoms of solid sodium and atoms of liquid sodium?

  1. Atoms of solid sodium have smaller atomic radii than atoms of liquid sodium.

  2. Atoms of solid sodium are more chemically reactive than atoms of liquid sodium.

  3. Atoms of liquid sodium move around more freely than atoms of solid sodium.

  4. Atoms of liquid sodium experience stronger attractive forces than atoms of solid sodium.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a liquid state, particles have more kinetic energy and move more freely than in a solid state, where they are fixed in a lattice. The other options are incorrect as atomic radii and chemical reactivity are properties of the element, not the state of matter.

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

You mix two colorless solutions and the resulting mixture becomes cloudy. What type of reaction was observed?

  1. A physical reaction

  2. A redox reaction

  3. A precipitation reaction

  4. An acid base reactions.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When two colourless solutions react to form a cloudy precipitate which settles at bottom of a solution then the reaction is said to be precipitation reaction.

Ex :- ${ AgNO } _{ 3 }+NaCl\rightarrow AgCl+{ NaNO } _{ 3 }$

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

Your lab partner mixed two colorless solutions in the test tube. He sees no observable changes in the resulting mixture and is unable to detect any change in temperature. Based on these observations, what type of reaction has taken place?

  1. A physical reaction

  2. A chemical reaction

  3. An exothermic reaction

  4. No reaction has taken place
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

No change in temperature $-$ neither exothermic  or endothermic reaction.

as no observable change $-$  not a chemical reaction
since the liquid mixed $-$ it is a physical change.

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

Dissolving sugar in water is an example of:

  1. physical change

  2. chemical change

  3. neutralisation

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

Sugar dissolves in water is a physical change because in this change no new substance is formed and the process is reversible in which by vaporization followed by condensation and crystallization water and sugar can be separated.