Explanation

Explanation

Explanation

Ernest Rutherford showed (1919) that nitrogen under alpha-particle bombardment ejects what appear to be hydrogen nuclei.

By 1920 Ernest Rutherford had accepted the hydrogen nucleus as an elementary particle, naming it proton.

while

Electron was discovered by J. J. Thomson in 1897.

Explanation

Explanation

Leafy vegetables such as spinach, kale, swiss chard, collard greens, and beet greens

They contain 2.5-6.4 mg of iron per cooked cup or 14-36% of  RDI.

Rich sources of iron include both animal and plant-based foods.

Heme iron, found in meat, poultry, and seafood, is more readily absorbed by the body.

Non-heme iron, found in plant-based foods, is also important, and its absorption can be enhanced by vitamin C. 

Explanation

Explanation

• Fluorine is the most electronegative element (3.98 on the Pauling scale).
• 7 valence electrons (2s² 2p⁵); needs one more for a stable noble gas configuration
• Small atomic radius → strong pull on bonding electrons
• High effective nuclear charge

Explanation

Limestone consists of calcium carbonate,

which has the chemical formula CaCO3.

Calcium carbonate is a chemical compound.

It is a common substance found in rocks as the minerals calcite.

Explanation

Methane is a chemical compound with the chemical formula CH4 (one carbon atom bonded to four hydrogen atoms).

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Explanation

A catalyst is a substance that speeds up a chemical reaction without being consumed or altered.

Catalysts increase the rate of reaction by lowering the activation energy required for the reaction to occur.