Answer : The correct option is, (D) 
Solution :
Formula used :
where,
Q = heat released = -1300 J
m = mass of water = 40 g
c = specific heat of water = 
= final temperature = ?
= initial temperature = 
Now put all the given values in the above formula, we get the final temperature of water.
Therefore, the final temperature of the water is,
Answer:
Nucleus
Explanation: it is the center of the atom, and contains protons and nuetrons
The answer is [OH⁻] = 1 x 10⁻⁴.
[OH⁻] = H₂O ÷ [H₃O⁺]
[OH⁻] = 1 x 10⁻¹⁴ / 1 x 10⁻¹⁰
[OH⁻] = 10⁻⁴
Answer : The mass of helium added to the cylinder was, 1.5 grams
Explanation :
Avogadro's law : It is defined as the volume of gas is directly proportional to the number of moles of gas at constant pressure and temperature.
or,
where,
= initial volume of gas = 2.00 L
= final volume of gas = 3.50 L
= initial moles of gas = 
= final temperature of gas = ?
Now put all the given values in the above equation, we get:
Now we have to calculate the mass of helium were added to the cylinder.
Mass of helium added = 3.5 - 2.00 = 1.5 g
Thus, the mass of helium added to the cylinder was, 1.5 grams
Answer: Option (b) is the correct answer.
Explanation:
Chemical properties are defined as the properties which tend to chemical composition of a substance. Neutral elements with similar number of valence electrons tend to show similar chemical properties as these have same reactivity which actually affects their chemical properties.
This means that elements of the same group tend to show similar chemical properties.
For example, oxygen and sulfur atom are both group 16 elements and they have 6 valence electrons. Therefore, they show similar chemical properties.
Thus, we can conclude that a pair of O and S elements is expected to be most similar in their chemical properties.
