0.400 g
20.5 g
103 g
Answer : The correct option is, 0.200 g
Solution :
As we know that the radioactive decays follow first order kinetics.
First we have to calculate the rate constant of a samarium-146.
Formula used :
Putting value of in this formula, we get the rate constant.
Now we have to calculate the original amount of samarium-146.
The expression for rate law for first order kinetics is given by :
where,
k = rate constant =
t = time taken for decay process =
a = initial amount of the samarium-146 = 205 g
a - x = amount left after decay process = ?
Putting values in above equation, we get the value of initial amount of samarium-146.
Therefore, the amount left of the samarium-146 is, 0.200 g
Ans: 0.200 g
Given:
Half life of Sm-146 = t1/2 = 103.5 million years
Time period, t = 1.035 billion years = 1035 million years
Original mass of sample, [A]₀ = 205 g
To determine:
Amount of sample after t = 1035 million years
Explanation:
The rate of radio active decay is given as:
Answer : The amount of polonium in the sample 966 days later is, 0.24 g
Solution :
Polonium-210 is a radioactive element.
Formula used :
where,
= the amount of polonium-210 remaining after 't' days
= the initial amount of polonium-210 = 31 g
t = time = 966 days
= half-life of the polonium-210 = 138 days
Now put all the given values in the above formula, we get
Therefore, the amount of polonium in the sample 966 days later is, 0.24 g
Answer:
6.43 moles of NF₃.
Explanation:
The balanced equation for the reaction is given below:
N₂ + 3F₂ —> 2NF₃
From the balanced equation above,
3 moles of F₂ reacted to produce 2 moles of NF₃.
Finally, we shall determine the number of mole of nitrogen trifluoride (NF₃) produced by the reaction of 9.65 moles of Fluorine gas (F₂). This can be obtained as follow:
From the balanced equation above,
3 moles of F₂ reacted to produce 2 moles of NF₃.
Therefore, 9.65 moles of F₂ will react to to produce = (9.65 × 2)/3 = 6.43 moles of NF₃.
Thus, 6.43 moles of NF₃ were obtained from the reaction.
Answer: A
Explanation: A is the answer
The Copernican model that is most similar to Aristarchus' . It is a simple and accurate heliocentric model that explains planetary motion with a small set of rules and a single underlying force.
The Copernican model that is most similar to that of Aristarchus is represented by Figure 6.31(b). In this model, Earth and other planets revolve around the Sun. It is a simpler and more accurate heliocentric model, similar to Aristarchus' idea of a heliocentric solar system. The Copernican model explains planetary motion with a small set of rules and a single underlying force, demonstrating the breadth and simplicity of the laws of physics.
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Answer: Option (D) is the correct answer.
Explanation:
The acetic acid, present in vinegar reacts wit magnesium and therefore, it releases hydrogen gas and magnesium acetate.
The chemical reaction will be as follows.
An acid is a substance which has pH less than 7 and changes blue litmus red. Acids taste sour as they are acidic in nature and releases hydrogen ions.
Whereas bases have pH greater than 7 and changes red litmus into blue.Bases taste bitter and releases hydroxide ions.
Thus, we can conclude that the statement it reacts with Mg to produce best describes the acid found in vinegar (acetic acid).
Answer:
D. It reacts with Mg to produce H2.