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3 years ago

10

Why is water considered a good solvent?

2 answers:

dem82 [27]3 years ago

7 0

Answer:

D: Water is polar, so it can form attractions to and pull apart molecules of many types of substances.

Explanation:

Water is an excellent solvent simply because its polar water molecules usually form hydrogen bonds with ions and polar molecules, thereby allowing the ionic and polar covalent compounds to easily disperse easily in water.

Thus, the correct option is; D

BartSMP [9]3 years ago

7 0

Answer: D

Explanation:

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Will give brainliest!!

givi [52]

A. Move the candle to the right, or the focal point to the left.

For a convex lens, the closer an object is to the focal point, the larger it’s image is (and therefore the greater the magnification is). The two ways you could make the candle be closer to the focal point are to move the candle to the right, or the focal point to the left.

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3 years ago

a stone is dropped from rest at an initial height h above the surface of the earth. Show that the speed with which it strikes th

Ksju [112]

Answer:

$v=\sqrt{2gh}$

Explanation:

We could use conversation of energy. Total distance the stone will cover will be

$h=\frac{1}{2} g t^{2}$

the Final velocity will be

$v=gt\\v=g\sqrt{\frac{2h}{g} }\\ v=\sqrt{2gh}$

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3 years ago

A 15.0 kg turntable with a radius of 25 cm is covered with a uniform layer of dry ice that has a mass of 9.0 kg. The angular spe

liubo4ka [24]

Answer:

ω₂=1.20

Explanation:

Given that

mass of the turn table ,M= 15 kg

mass of the ice ,m= 9 kg

radius ,r= 25 cm

Initial angular speed ,ω₁ = 0.75 rad/s

Initial mass moment of inertia

$I_1=\dfrac{M+m}{2}r^2$

$I_1=\dfrac{15+9}{2}\times 0.25^2\ kg.m^2$

$I_1=0.75\ kg.m^2$

Final mass moment of inertia

$I_2=\dfrac{M}{2}r^2$

$I_2=\dfrac{15}{2}\times 0.25^2\ kg.m^2$

$I_2=0.468\ kg.m^2$

Lets take final speed of the turn table after ice evaporated =ω₂ rad/s

Now by conservation angular momentum

I₁ ω₁ =ω₂ I₂

$\omega_2=\dfrac{0.75\times 0.75}{0.468}\ rad/s$

ω₂=1.20

7 0

3 years ago

The angular velocity of a flywheel obeys the equa tion w(1) A Br2, where t is in seconds and A and B are con stants having numer

makkiz [27]

Answer:

$A \to rad/s$

$B \to rad/s^3$

Explanation:

$\omega_z(t)=A + Bt^2$

Required

The units of A and B

From the question, we understand that:

$\omega_z(t) \to rad/s$

This implies that each of $A$ and $Bt^2$ will have the same unit as $\omega_z(t)$

So, we have:

$A \to rad/s$

$Bt^2 \to rad/s$

The unit of t is (s); So, the expression becomes

$B * s^2 \to rad/s$

Divide both sides by $s^2$

$B \to \frac{rad/s}{s^2}$

$B \to rad/s^3$

5 0

3 years ago

How many neutrons does element X have if its atomic number is 23 and its mass number is 90?

givi [52]

Answer:

67

Explanation:

- The atomic number (Z) of an atom is equal to the number of protons in the nucleus

- The mass number (A) of an atom is equal to the sum of protons and neutrons in the nucleus

Therefore, calling p the number of protons and n the number of neutrons, for element X we have:

Z = p = 23

A = p + n = 90

Substituting p=23 into the second equation, we find the number of neutrons:

n = 90 - p = 90 - 23 = 67

4 0

4 years ago

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