It should be a chemical change
Answer:
1.25 gram of cesium-137 will remain.
Explanation:
Given data:
Half life of cesium-137 = 30 year
Mass of cesium-137 = 5.0 g
Mass remain after 60 years = ?
Solution:
Number of half lives passed = Time elapsed / half life
Number of half lives passed = 60 year / 30 year
Number of half lives passed = 2
At time zero = 5.0 g
At first half life = 5.0 g/2 = 2.5 g
At 2nd half life = 2.5 g/ 2 = 1.25 g
Thus. 1.25 gram of cesium-137 will remain.
Answer: Option B
Explanation: when strong acid react with strong base, the resulting solution is neutral as in the case of HCl and NaOH
HCl + NaOH —> NaCl + H2O
From the equation obtained, The salt ( NaCl) obtained is a normal salt which is neutral.
Generally, chemists prefer to use morality (B) because it only invovles measuring the final volume of the solution and amount of moles of the solute
Hope this helps
