Answer:
Explanation: Mendeleev arranged the elements on the basis of their atomic mass. Melting and boiling point were used as the physical characteristics in deciding the position of elements. He arranged the elements and wrote the formula of their oxides and hydrides which seemed to possess same chemical formula.
Explanation:
In a water molecule, the oxygen atom and hydrogen atoms share electrons in covalent bonds, but the sharing is not equal. In the covalent bond between oxygen and hydrogen, the oxygen atom attracts electrons a bit more strongly than the hydrogen atoms.
Answer
A chemical change happens when one chemical substance is transformed into one or more different substances, such as when iron becomes rust. Chemical changes occur through the process of chemical reactions, and the resulting substances have different properties because their atoms and molecules are arranged differently.
Physical changes are changes affecting the form of a chemical substance, but not its chemical composition. Physical changes are used to separate mixtures into their component compounds, but can not usually be used to separate compounds into chemical elements or simpler compounds
Explanation:
Answer:
k = 4.85 x 10⁻³ / s
Explanation:
For a first order reaction we have two very important equations we need to memorize:
ln ( N/N₀ ) = -kt
and,
0.693/ k = t₁/₂
where k is the rate constant and t i is the halflife which can be derived from the first equation.
0.693/ k = t₁/₂ ⇒ k = 0.693 / t₁/₂
k = 0.693 / 143 s = 4.85 x 10⁻³ / s
