Q1: Wave length of X-rays is about 1 angstron, however it can not pass through a sheet of

ANS:C - lead

Lead is a metallic element with the chemical symbol Pb and atomic number 82. It is a soft, dense, and malleable metal with a bluish-white color when freshly cut, but it quickly tarnishes to a dull gray when exposed to air. Here's an explanation of some key aspects of lead:

1. Physical Properties: Lead is a heavy metal with a density of 11.34 grams per cubic centimeter, making it one of the densest common metals. It has a relatively low melting point of 621.5 degrees Fahrenheit (327.5 degrees Celsius) and a boiling point of 3,180 degrees Fahrenheit (1,749 degrees Celsius). Lead is soft and malleable, allowing it to be easily shaped and formed into various objects.
2. Chemical Properties: Lead is a relatively stable metal and is resistant to corrosion in most environments. However, it reacts slowly with moist air and acidic substances, forming a thin layer of lead oxide (PbO) or lead carbonate (PbCO3) on its surface, which provides some protection against further corrosion.
3. Applications: Lead has been used by humans for thousands of years due to its various useful properties. Some common applications of lead include:
   • Batteries: Lead-acid batteries are widely used in vehicles, uninterruptible power supplies (UPS), and backup power systems.
   • Construction: Lead is used in construction materials, such as lead flashing, roofing, and pipes, due to its corrosion resistance and ability to block radiation.
   • Radiation shielding: Lead is highly effective at blocking radiation, including X-rays, gamma rays, and nuclear radiation. It is used as a shielding material in medical imaging devices, radiation therapy rooms, nuclear reactors, and nuclear waste storage facilities.
   • Ammunition: Lead is used in bullets and shot due to its density, which provides good ballistic properties.
   • Solder: Lead-based solders have been traditionally used in electronics and plumbing applications for their low melting point and excellent solderability.
4. Health Concerns: Despite its usefulness, lead is toxic to humans and other organisms. Exposure to high levels of lead can lead to serious health effects, including neurological damage, developmental disorders, and organ damage. As a result, there are strict regulations regarding the use of lead in consumer products, drinking water, and industrial processes to minimize exposure and prevent lead poisoning.