Chemistry Test - 3

Gold metal is formed from gold chloride in solution-gold metal is formed from gold chloride in solution.

iron + water + oxygen → hydrated iron(III) oxide ( hydrated ferric oxide)

Rust forms when oxygen reacts with iron in presence of water/moisture.

The iron oxide reacts with oxygen to yield red rust, Fe₂O₃.H₂O.

Chlorine (Cl) is a member of the halogen group with an atomic number of 17.

It is the second most common halogen on Earth

Chlorine in its pure form is yellowish-green, but its common compounds are typically colourless

Chlorine is vital for living organisms although highly concentrated pure chlorine is dangerous to living beings.

Chlorine has two stable isotopes, Cl-35 and Cl-37 while Cl-36 is radioactive.

Electropositive character of an element is its ability to lose electrons and form positive ions. Now, as on moving from left to right in a period of periodic table, the nuclear charge increases due to the gradual increase in number of protons, so the valence electrons are pulled more strongly by the nucleus. Thus, it becomes more and more difficult for the atoms to lose electrons causing a decrease in the electropositive character of elements.

According to De-broglie's formula-

$\lambda =\frac{h}{mv}$

where $\lambda =$ wavelength

$h=$ Planck's constant

$v=$ velocity of the ball

On substituting the values we get,

$\lambda =\frac{6.6\times {10}^{-34}}{0.5\times 100}$

$\lambda =1.32\times {10}^{-35} m$

The element hydrogen has no neutrons because its atomic number and mass number are same. The number of neutrons is obtained on taking the difference between atomic number and mass number. Due to same atomic number and mass number, the difference between them is zero.

Sulphur and Gold are element while air is mixture of various compound made of element Hydrogen and Oxygen and its Chemical formula is H₂O.

The solids are characterized by incompressibility, rigidity and mechanical strength.

The molecules, atoms or ions in solids are closely packed, i.e., they are held together by strong forces and cannot move about at random. Hence solids have definite volume, shape, slow diffusion, low vapour pressure and possess the unique property of being rigid.

Given:

The pH of the solution is \(5.4\).

We know that the \({pH}\) of a solution is given by:

\(p H=-\log_{10} \left[H^{+}\right]\)

Substituting \({pH}=5.4\), we get:

\(5.4=-\log_{10} \left[H^{+}\right]\)

\(\Rightarrow{\left[H^{+}\right]=10^{-5.4}=3.98 \times 10^{-6}}\)

Therefore, the concentration of Hydrogen ion is \(3.98 \times 10^{-6}\).