The statement best explains why the thermometer reading initially increases when LiBr(s) is dissolved in the water is the dissolving of the LiBr(s) in water is an exothermic process.
A thermometer is an instrument that is used to measure the temperature of an object.
An exothermic process is in which the heat and energy is released in the outer system.
Thus, the correct option is (4) The dissolving of the LiBr(s) in water is an exothermic process.
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Answer:
A. The cumulative nature of science.
Explanation:
(2) They differ in their properties, only.
(3) They differ in their molecular structure and properties.
(4) They do not differ in their molecular structure or properties.
Answer: Option (3) is the correct answer.
Explanation:
When an element exists in two or more different physical forms then they are known as allotropes.
For example, diamond and graphite are both allotropes of carbon.
In graphite, carbon atoms are joined together in sheets of six sided lattice. Whereas in diamond, carbon atoms are joined together in four cornered lattice.
Therefore, as these allotropes are made up of same element so they have similar chemical properties but different physical properties like melting point, boiling point etc.
Also, both of them have different molecular structure.
Thus, we can conclude that the statement the differ in their molecular structure and properties correctly describes diamond and graphite.
(2) 2 (4) 18
Answer: (3) 15
Explanation: We criss-cross down the oxidation numbers to get the subscripts for the correct formulas. That means the X has an oxidation number of 5. The element with the + oxidation number is always written first so it is +5. Of the groups names, only group 15 has +5 as an oxidation number.
Answer:
Average atomic mass = 79.9034 amu
Explanation:
The formula for the calculation of the average atomic mass is:
Given that:
For first isotope:
% = 50.69 %
Mass = 78.9183 amu
For second isotope:
% = 49.31 %
Mass = 80.9163 amu
Thus,
Average atomic mass = 79.9034 amu
(2) Chlorine molecules have strong covalent bonds.
(3) Chlorine molecules have weak intermolecular forces of attraction.
(4) Chlorine molecules have strong intermolecular forces of attraction.