Answer is: boron (¹¹B).
1) Carbon (¹²C) is element with atomic number 6 and mass number 12. Atomic number (Z) is the number of protons, which is characteristic of a chemical element.
Z(C) = p⁺ = 6.
A = p⁺ + n°; mass number is the total number of protons and neutrons in a nucleus.
A(C) = 12.
n°(C) = 12 - 6.
n°(C) = 6; number of neutrons.
2) Boron (¹¹B) is element with atomic number 5 and mass number 11.
Z(B) = p⁺ = 5.
A(B) = 11.
n°(B) = 11 - 5.
n°(B) = 6; number of neutrons in boron.
B. barium (Ba)
C. cesium (Cs)
D.rubidium (Rb)
Answer: Option (A) is the correct answer.
Explanation:
When we move downwards in a group then size of the atom increases due to which there is less force of attraction between the nucleus and valence electrons of the atom.
Hence, the atom can easily loose electrons. As a result, reactivity of elements increases down the group.
But when we move across a period then there is decrease in reactivity of the atoms as size of atoms decreases due to which there is an increase in force of attraction between the nucleus and valence electrons.
Therefore, atoms are unable to lose electrons easily.
Hence, magnesium is less reactive than both sodium and strontium. Whereas except magnesium rest all options are more reactive than sodium and strontium.
Thus, we can conclude that magnesium is likely to be less reactive than both strontium and sodium.
b. Oxygen
c. Hydrogen
d. Nitrogen
Answer: The correct answer is Option d.
Explanation:
Dry air is composed of a mixture of gases like argon, oxygen, nitrogen, carbon dioxide and many other gases present in trace amount.
The percentage of these gases by volume in dry air is:
Carbon dioxide = 0.03%
Argon = 0.93%
Oxygen = 20.95%
Nitrogen = 78.09%
Hydrogen = Trace amounts
From the above percentage values, we can easily say that nitrogen has the highest percentage by volume in dry air. Hence, the correct option is d.
Answer: Option (b) is the correct answer.
Explanation:
Elements which belong to same group show similar chemical properties.
This is because elements which are present in the same group have same number of valence electrons. Hence, they tend to show same type of reactivity which makes them exhibit similar chemical properties.
As chemical properties are defined as the properties which tend to show difference in chemical composition of a substance.
For example, toxicity, reactivity, combustion etc are all chemical properties.
Here, oxygen and sulfur are both group 16 elements. So, they tend to show similar chemical properties.
Thus, we can conclude that oxygen and sulfur elements have the most similar chemical properties.
Among the given pairs, oxygen and sulfur display the most similar chemical properties because they are in the same group of the periodic table (Group 16, or the chalcogens), and thus have the same number of valence electrons (six), leading to similar chemical reactivity.
Among the pairs of elements presented in the original question (boron and carbon, oxygen and sulfur, aluminum and bromine, argon, and silicon), the pair that has the most similar chemical properties is oxygen and sulfur. This is due to their placement within the same group on the periodic table, specifically the chalcogens, or Group 16.
Elements in the same group of the periodic table typically exhibit similar chemical properties because they have the same number of valence electrons. For example, boron and carbon, although neighbors on the periodic table, do not exhibit highly similar chemical properties due to their different numbers of valence electrons.
On the other hand, oxygen and sulfur, both being members of Group 16, have six valence electrons and thus exhibit similar chemical reactivity and form similar types of compounds, despite their differences in physical properties.
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As the barium hydroxide solution is added to the solution of sulfuric acid, the electrical conductivity of the acid solution decreases because the
(1) volume of the reaction mixture increases
(2) temperature of the reaction mixture decreases
(3) concentration of ions increases
(4) concentration of ions decreases
As the barium hydroxide solution is added to the solution of sulfuric acid, The conductivity would decrease because the concentration of ions decreases. Thus option 4 is correct.
Electric conductivity can be defined as the measure of the mechanism of electric current moves within a substance, greater the electrical conductivity within the material higher will be the current density.
The electrical conductivity is the ability of a substance that involve in conduction of electricity, the conductivity of a material is important for example the wire conductors need to let current to flow as easily.
When barium hydroxide dissolve in a solution called sulphuric acid, the Barium ions replace the hydrogen ions and an insoluble solid doesn't contribute ions.
Thus option 4 is correct.
Learn more about conductivity, here:
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Answer:
2) condensing of water vapor
Explanation:
Entropy is the measure of disorder in a system. Disorder means how "separated" and distanced the molecules, particles, etc. are from each other. Solids and crystals have rigid structures meaning that they have less disorder than gases and liquids that have free structures. Gases and liquids have a higher disorder than solids and crystalline structures. An increase in entropy means that the disorder is increasing; more heat and energy are being added. A decrease in entropy means that the disorder is decreasing and the structure becomes more rigid and ordered; less heat and energy are being added. So the condensing of water vapor means that disorder is decreasing, thus the entropy is decreasing.
I hope this makes sense :)
(1) -153°C (3) +293°C
(2) -120.°C (4) +393°C
The temperature 120 K converts to -153°C. This conversion is made by subtracting 273.15 from the Kelvin temperature.
To convert Kelvin (K) to Celsius (°C), you subtract 273.15 from the Kelvin temperature. For example, 120 K becomes 120 - 273.15, equaling -153.15°C. Rounded, this is approximately -153°C. It's essential to note that 0 K is absolute zero, representing the lowest possible temperature, which corresponds to -273.15°C on the Celsius scale. Therefore, the correct answer is (1) -153°C. This conversion is fundamental in relating temperatures on the Kelvin and Celsius scales, where Celsius measures temperature relative to the freezing and boiling points of water, and Kelvin starts from absolute zero, the absence of thermal energy.
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