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Gamma camera observes radiation from concentrated in organs:
A metal oxide has the formula M$_{0.98}$O. The metal M exists as M$^{2+}$ and M$^{3+}$ ions. What fraction of the metal exists as M$^{3+}$?
Let $x$ = fraction of M as M$^{3+}$, $(0.98 - x)$ = fraction as M$^{2+}$.
Charge balance (O$^{2-}$ contributes $-2$): $2(0.98-x) + 3x = 2$
$1.96 - 2x + 3x = 2$
$x = 0.04$
Fraction of M as M$^{3+}$ $= \dfrac{0.04}{0.98} \times 100 \approx \mathbf{4.08\%}$
Descriptive research describes what exists — it documents characteristics, behaviors, and conditions — but does not establish cause-and-effect or make predictions. Associational (correlational) research can identify relationships but not causality. Only experimental (intervention) research can make causal claims.
Correct Answer: B — Descriptive.
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