Chemistry

Potassium is an alkali metal and is soft enough to be cut with a knife, unlike the other options which are harder transition or post-transition metals.

Sir Humphry Davy isolated Barium in 1808 using electrolysis of molten barium salts.

Daniel Rutherford is credited with the discovery of nitrogen in 1772. He isolated it by removing oxygen and carbon dioxide from air.

Boron was isolated independently in 1808 by two separate groups: Sir Humphry Davy, and the team of Joseph Louis Gay-Lussac and Louis Jacques Thenard.

Joseph Priestley is widely credited with the discovery of oxygen in 1774, when he isolated it by heating mercuric oxide.

Martin Heinrich Klaproth discovered uranium in 1789 while analyzing pitchblende ore. He named the element after the planet Uranus.

Correct answer is (1). 

Uranium is the heaviest naturally occurring element found in significant quantities on Earth, often cited as the most complex natural element.

Scuba divers use a mixture of helium and oxygen, known as heliox, to prevent nitrogen narcosis and oxygen toxicity at greater depths.

Correct answer is (1). 

Yellowcake is a concentrated form of uranium oxide, which is an intermediate step in the processing of uranium ore.

Monazite is a reddish-brown phosphate mineral that is a primary ore for thorium, as well as rare earth elements.

Cerussite is a mineral form of lead carbonate and is one of the most important ores of lead.

Aluminum bronze is a type of bronze where aluminum is the main alloying metal; it is highly resistant to corrosion and is commonly used for coins and statues.

Alnico is an alloy consisting primarily of aluminum, nickel, and cobalt, and is widely used for making permanent magnets.

Talc is a clay mineral composed of hydrated magnesium silicate with the chemical formula Mg3Si4O10(OH)2.

Dolomite is a calcium magnesium carbonate mineral. Limonite, Siderite, and Magnetite are all common iron ores.

Pitchblende, also known as uraninite, is the primary ore of uranium.

Malachite is a copper carbonate hydroxide mineral, commonly used as an ore of copper.

Feldspars are a group of rock-forming tectosilicate minerals that make up about 41 percent of the Earth's continental crust by weight, making them the most plentiful minerals.

Duralumin is a hard, strong, lightweight alloy of aluminum, copper, manganese, and magnesium, widely used in aircraft construction.

Silumin is an aluminum-silicon alloy known for its good casting properties, making it suitable for engine parts.

Magnalium is an alloy of aluminum and magnesium, valued for its strength and corrosion resistance, often used in external parts of ships and steamers.

Nickel steel is known for its toughness and resistance to wear, making it ideal for high-stress applications like drills and crankshaft bearings.

Chrome steel is known for its hardness and high tensile strength, which are essential for manufacturing durable tools and springs. While it is used in automotive parts, it is specifically valued for its resilience in tool making.