Which of these is not a property of minerals?

Which of the following statements is FALSE?

Jobisdone [24]

Answer:

Option C is false statement. The half life of a second order reaction is not dependent on concentration.

Explanation:

Half life of a reaction is defined as the amount of time which is required for a reactant concentration reduced by half comparison to its initial concentration.

Half life of a second order reaction is depend on the initial concentration of a reaction, in contrast to 1st order reaction.

7 0

2 years ago

The work function for metallic potassium is 2.3 eV. Calculate the velocity in km/s for electrons ejected from a metallic potassi

mote1985 [20]

Answer:

932.44 km/s

Explanation:

Given that:

The work function of the magnesium = 2.3 eV

Energy in eV can be converted to energy in J as:

1 eV = 1.6022 × 10⁻¹⁹ J

So, work function = $2.3\times 1.6022\times 10^{-19}\ J=3.68506\times 10^{-19}\ J$

Using the equation for photoelectric effect as:

$E=\psi _0+\frac {1}{2}\times m\times v^2$

Also, $E=\frac {h\times c}{\lambda}$

Applying the equation as:

$\frac {h\times c}{\lambda}=\psi _0+\frac {1}{2}\times m\times v^2$

Where,

h is Plank's constant having value $6.626\times 10^{-34}\ Js$

c is the speed of light having value $3\times 10^8\ m/s$

m is the mass of electron having value $9.11\times 10^{-31}\ kg$

$\lambda$ is the wavelength of the light being bombarded

$\psi _0=Work\ function$

v is the velocity of electron

Given, $\lambda=260\ nm=260\times 10^{-9}\ m$

Thus, applying values as:

$\frac{6.626\times 10^{-34}\times 3\times 10^8}{260\times 10^{-9}}=3.68506\times 10^{-19}+\frac{1}{2}\times 9.11\times 10^{-31}\times v^2$

$3.68506\times \:10^{-19}+\frac{1}{2}\times \:9.11\times \:10^{-31}v^2=\frac{6.626\times \:10^{-34}\times \:3\times \:10^8}{260\times \:10^{-9}}$

$\frac{1}{2}\times 9.11\times 10^{-31}\times v^2=7.64538\times 10^{-19}-3.68506\times 10^{-19}$

$\frac{1}{2}\times 9.11\times 10^{-31}\times v^2=3.96032462\times 10^{-19}$

$v^2=0.869446\times 10^{12}$

v = 9.3244 × 10⁵ m/s

Also, 1 m = 0.001 km

5 0

2 years ago

Identify the compound with the smallest percent ionic character. identify the compound with the smallest percent ionic character

rosijanka [135]

<span> I'll try. A purely ionic bond, as the name implies is a bond between ions. If that sounds like double-talk it's because some ionic compounds are more ionic than others. A purely covalent compound is one in which the electrons are shared EQUALLY. It turns out that the only compounds in which the electrons are shared equally is one in which both atoms sharing the electrons are of the same element. For example O2, N2, Cl2, I2 or F2. Now suppose you make a compound between Fluorine and Iodine, IF. Since fluorine has a greater attraction for electrons than iodine, the bond will be polar. That is the fluorine part of the molecule will be negative and the iodine part will be positive. The attraction for electrons isn't equal. The same thing happens with ionic bonds. In your first question, the ionic character decreases from NaF through SiF4. Sodium loses an electron quite readily because it achieves a stable neon like configuration. Fluorine attracts an electron very strongly for the same reason. But as you move across the period, two things are happening. First, look at SiF4. Silicon is right in the middle of the period, It can achieve a stable inert gas configuration either by gaining 4 or losing 4 electrons. So it depends upon the electronegativity (the electron grabbing ability) of the atom it's combining with. Since Fluorine has the highest electron grabbing ability of any of the reactive elements, it will tend to pull the electrons away from silicon. But silicon doesn't completely give them up as it would in a purely ionic compound. AlF3 is similar but will tend to give up 3 electrons a little easier than SiF4. MgF2 is even more ionic because it's approaching an inert gas configuration and only need to lose 2 electrons. Can you see what's happening? The closer you get to the middle of a period, the less likely an atom is to give up COMPLETELY its electrons. In question 2 your answer is CO. The elements are close together (which means that their electronic structure is similar) and carbon, like silicon is in the middle of the period so its more likely to share electrons than it is to give them up (form an ionic bond). So it turns out that most chemical bonds are neither completely ionic or covalent but lie in between the two extremes and are called polar covalent. I hope this helps.</span>

4 0

2 years ago

A(n) ________________ is a structure or behaviors in organisms that help them survive in their environment.

Lapatulllka [165]

Answer:

Adaptations

Explanation:

Adaptation is simply defined as a specific characteristics of an animal or plant which can be a body part, body covering, or behavior that helps an animal or plant survive in its environment.

The common types of Adaptations includes Physical adaptation which entails a change to a part of the body and Behavioral adaptation which is simply what an animal does in response to an external stimulus.

Examples of Adaptation includes Hibernation, Camouflage, Mimicry, Whiskers, Beaks and others. In plants, seed colour, hard endocarp, secretions e. t. c helps them survive in their environment.

6 0

2 years ago

If the molar mass of NaCl is 58.44 g/mol, what amount of NaCl (in mol) is contained in 250.0 mg of NaCl?

4vir4ik [10]

Answer: 0.004 moles

Explanation:

Amount of substance= mass/ molar mass

Mass= 250mg or 0.25g

Molar mass= 58.44gmol-1

Amount= 0.25/58.44

= 0.004 moles

5 0

2 years ago