Answer:
A
Explanation:
a. True
b. False
1. Which of the following items represents a chemical change? burning melting evaporation freezing
Answer:
Explanation:
Chemical properties depend on composition while physical properties do not depend on composition. As in case of burning, composition changes due to this , this is chemical properties while freezing, melting and evaporating process, composition remain same, so these have physical properties, like water in liquid, ice and vapor state have same composition.
2. The physical properties of a compound are similar to those of its elements.
Answer:
Explanation:
In the context of Chemistry, 'Burning' is a chemical change as it results in new substances. The claim that a compound's physical properties are similar to its elements is typically false as the properties often differ significantly, an example being the difference between water and its constituent elements hydrogen and oxygen.
The question falls under the field of Chemistry. It refers to the concept of chemical and physical changes in matter. A chemical change is a change in matter that results in the formation of one or more new substances with new properties. On the contrary, a physical change relates to a change in the state of matter without any change in its chemical composition. Out of the options given, the process of 'Burning' symbolizes a chemical change as it results in the formation of new substances such as carbon dioxide, water vapor, etc.
As for the second part of your question, the statement that 'physical properties of a compound are similar to those of its elements' is generally false. The properties of a compound often differ greatly from those of the constituent elements. One classic example is that of water (H2O). Water is a liquid at room temperature, quenches thirst, and is essential for life. However, its constituent elements - Hydrogen and Oxygen - are both gases and do not possess these characteristics.
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2.)lithium + oxygen to lithium oxide
3.)oxygen + lithium to lithium + oxide
4.)lithium oxide to lithium + oxygen
The correct answer is the second option. The wordequation that would represent the formation of lithium oxide from lithium metal and oxygen is:
lithium + oxygen to lithium oxide
Inchemical symbols, the balanced chemical equation is expressed as:
Li + O2 = Li2O
Answer : The correct option is, (2) lithium + oxygen to lithium oxide
Explanation :
When the lithium react with the oxygen to give lithium oxide as a product.
The balanced chemical reaction will be,
This reaction can be represented in words as,
Lithium react with oxygen to give lithium oxide.
or,
lithium + oxygen to lithium oxide
Hence, the correct option is, (2) lithium + oxygen to lithium oxide
It is a strong base and a very poor conductor of electric current.
B.
It is a strong acid and a very good conductor of electric current.
C.
It is a weak base and a very good conductor of electric current.
D.
It is a weak acid and a poor conductor of electric current.
Substance A is mixed with water and donates 0.4% of its H⁺ ions, therefore given substance is a weak acid & show poor conduction of electric current.
According to the Arrhenius theory of acids and bases, acids are those species which gives H⁺ ion to the solution.
In the question it is given that, substance A is mixed with water and it donates H⁺ ion, from this it is clear that given substance is acid. It is also mention that it donates only 0.4% of its H⁺ ion means partial dissociation is observed, so we conclude that this acid is weak in nature. And due to weak dissociation and less number of available H⁺ ion it did not conduct electricity effectively.
Hence, option (D) is correct i.e. it is weak acid and a poor conductor of electric current.
To know more about acids, visit the below link:
Answer:
D
Explanation: