The half-life of a radioisotope is the time required for its activity to reduce to:
A. Zero
B. One-half of the initial value
C. One-fourth
D. Three-fourths
Answer: Option B
Solution (By JKExamLibrary)
Half-life (T₁/₂) is the time taken for the number of radioactive nuclei (or activity) to decrease to half of its original value. It's a constant characteristic of each radioisotope. For example, C-14 half-life is 5730 years.
Explanation:
Mg + 2HCl → MgCl₂ + H₂↑. Magnesium displaces hydrogen from acid. This is a single displacement and redox reaction. Copper does not react similarly.
Explanation:
Ammonium chloride sublimes on heating; it converts directly from solid to vapor, leaving behind common salt. The vapors can be condensed on a cold surface to obtain solid NH₄Cl. This method works for any mixture where one component sublimes and the other does not.
Explanation:
Atomic number = 2+8+7=17 (chlorine). Period = number of shells = 3. Valence electrons = 7 → Group 17 (10+7 for p-block). Group 18 has 8 valence electrons.
No comments yet. Be the first to start the discussion!