Answer:
B
Explanation:
Chemistry is the study of matter, its composition and the changes it undergoes.
<span>A.H2O = water, so it is a liquid at room temperatures (melting point = 0C) and melting point must be below 20C
B.HCl = A gas at room temperatures, so melting point (-114C) is definitely lower than 20C.
Melting points of the aqueous solution (solution in water) at different concentrations are all below that of water, i.e. 0C.
C.CH4 = A gas at room temperatures, so melting point (-182C) must be below 20C.
D.MgCl2 = A white powdery solid at room temperatures, so its melting point (714C) must be above 20C (So this is the only one among the four choices that melts above 20 ° C).</span>
1. U₂₃₈→α→Th₂₃₄(UX₁)
<span>2. Th₂₂₈→α→Ra₂₂₆(MsTh₁) </span>
<span>α = Alpha decay (release of He Nucleus) </span>
<span>The decay products are meso states that undergo further (β) decay</span>
Don't touch your eyes.
Never taste-test unless the teacher tells you to.
Do not touch anything without directions.
Wear safety goggles.
Wash your hands after each experiment.
Wear proper lab clothes.
Do not mishandle lab equipment.
Clean up your workplace.
Act serious; no horseplay!
Report accidents to the teacher right away!
Have a great day, scholar!
