Answer: B. Allow light to pass through. :)
<span>1. A cylinder is submerged in water as illustrated in the diagram. Which of the following statements is true?
</span><span>The pressure at D is greater than at B. This is because D is trying to get back to the surface with an amount of pressure. B has less amount of pressure.
</span><span>2. A cylinder is submerged in water as illustrated in the diagram. If the area of the top and the bottom of the cylinder is the same, which of the following statements is true?
</span><span>buoyant force = (force D - force A).
Edit: If you ever notice. When you fill a sink full of water. Put a glass upside down and try forcefully to submerge it under the water it will resist. This is because of the pressure and air. The glass is less dense then water. (Also depends on the glass)</span>
Answer: Option (4) is the correct answer.
Explanation:
It is known that density is mass divided by volume.
Mathematically, Density = 
Since, density is directly proportional to mass. So, more is the mass of an element more will be its density.
Mass of magnesium is 24.305 g/mol.
Mass of barium is 137.327 g/mol.
Mass of beryllium is 9.012 g/mol
Mass of radium is 226 g/mol.
Hence, radium has more mass therefore it will have the greatest density at STP.