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3 years ago

Why are scientists concerned with finding Earth-like planets?

2 answers:

8 0

Because although these planets are much like earth, they may not be able to support life as they may not contain the necessary components to allow humans to live in the planets.

sdas [7]3 years ago

5 0

Over the last few days, NASA has been getting everybody excited with its plans to hold a high profile briefing about a discovery beyond our solar system. Now we know that the announcement concerns the discovery of seven planets orbiting a star elsewhere in our galaxy. hope this helps

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Why are outer electrons of some substances able to be removed by friction?

svlad2 [7]

The outer electrons are not as tightly bound as ones closer to the nucleus

8 0

3 years ago

Read 2 more answers

A gas evolved during the fermentation of sugar was collected at 22.5°C and 702 mmHg. After purification its volume was found to

miskamm [114]

Answer:

A) 0.95 mol

Explanation:

We will assume the gas given off in the fermentation is an ideal gas because that allows us to use the ideal gas equation.

PV = nRT

First let's convert all measurements to units that we can use

P = 702 mmHg * 1 atm/760 mmHg = 0.92368 atm

V = 25.0 L

R = 0.08206 L-atm/mol-K

T = 22.5 °C +273.15 = 295.65 K

PV = nRT

0.92368 atm * 25.0 L = n * 0.08206 L-atm/mol-K * 295.65 K

n = 0.9518 mol

4 0

3 years ago

Determine the pH of 0.050 M HCN solution. HCN is a weak acid with a Ka equal to 4.9 x 10-10 DONE

nadezda [96]

Answer:

The pH of the solution is 5.31.

Explanation:

Let " $\alpha$ is the dissociation of weak acid - HCN.

The dissociation reaction of HCN is as follows.

$HCN+H_{2}O\rightarrow H_{3}O^{+}+CN^{-}$

Initial C 0 0

Equilibrium c(1- $\alpha$ ) c $\alpha$ c $\alpha$

Dissociation constant = $Ka= c\alpha \times \frac{c\alpha}{c(1-\alpha)}$

$=\frac{c\alpha^{2}}{(1-\alpha)}$

In this case weak acids $\alpha$ is very small so, (1- $\alpha$ ) is taken as 1.

$Ka=C\alpha^{2}$

$\alpha=\sqrt\frac{ka}{c}$

From the given the concentration = 0.050 M

Substitute the given value.

$\alpha=\sqrt\frac{4.9\times 10^{-10}}{0.05}=9.8\times 10^{-4}$

$[H_{3}O^{+}]=c\alpha$

$[H_{3}O^{+}]=0.05\times 9.8\times 10^{-4}= 4.9\times10^{-6}$

$pH= -log[H_{3}O^{+}]$

$=-log[4.9\times10^{-6}]$

$=6-log 4.9= 5.31$

Therefore, The pH of the solution is 5.31.

7 0

3 years ago

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An atom of 70kr has a mass of 69. 955264 amu. mass of1h atom = 1. 007825 amu mass of a neutron = 1. 008665 amu. calculate the bi

Leno4ka [110]

The binding energy in MeV per atom is - 63284.56 Mev.

The amount of energy needed to detach a particle from a system of particles or to disperse every particle in the system is known as the binding energy. Subatomic particles in atomic nuclei, electrons attached to atom's nuclei, and atoms and ions bonded together in crystals are three examples of where binding energy is very relevant.

If we have a nucleus with Z protons and N neutrons and mass MA, where A = Z + N then its binding energy in MeV is given by: Eb(MeV) = (Zmp + Nmn - MA) x 931.494 MeV/u

Mass of atom = 69.955264 amu

Mass of proton = 1.007825 amu

Mass of neutron = 1.008665 amu

Binding energy, Mev = (Zmp + Nmn - M) × 931.494MeV/u

= ( 1.007825 + 1.008665 - 69.955264) × 931.494

= - 67.938774 × 931.494

= - 63284.56 Mev

Therefore, the binding energy in MeV per atom is - 63284.56 Mev.

Learn more about binding energy here:

brainly.com/question/16795451

#SPJ4

3 0

2 years ago

What is the smallest substance? 1 .mixture 2 .compound 3 .element

Andrew [12]

Number 3 it’s element

8 0

3 years ago

Read 2 more answers