a. Define Valency. b. Write the symbol and valency of the following : (i) Oxygen (ii) potassium 7. a. Magnesium burns in Oxygen to form Magnesium Oxide. a) Name the reactants b) Name the Products c) Write the word equation for the above reaction.

Answer:

Dark matter is the term astronomers use to describe material in the universe that does not emit or reflect light and is, therefore, invisible.

Explanation:

Stars, nebulae, and galaxies are examples of luminous objects in the sky. However, luminous matter appears to make up only a small fraction of all the matter in the universe, perhaps only up to 10 percent.

Answer:

Because the air can move out of the balloon at such a speed, it propells the balloon forward.

Explanation:

SmolFox no longer exists

~Chad~

The action of the balloon pushes against the balloon moving it in the backward direction

Newton's third law of motion states that every action have a equal and opposite reaction . If object A  exert force on object B , then object B will also exert an equal and opposite force on object A . Forces result from interaction of two bodies .

As we know according to Newton's third law of motion , when the air rushes out and pushes against the air which pushes  the balloon to move in opposite direction , the action of the balloon pushes against the balloon moving it in the backward direction

learn more about  Newton's third law of motion

https://brainly.com/question/974124?referrer=searchResults

#SPJ3  

Answer:

The distance of the light is 9.4608 x 10^25 m

Explanation:

Time taken by the light = 10 billion years = 10 x 10^9 years

speed of light = 3 x 10^8 m/s

speed of light in m/years is = (3 x 10^8)/(60 x 60 x 24 x 365) = 9.4608 x 10^15 m/year

distance = speed x time

therefore, the distance of this light = 10 x 10^9 x 9.461 x 10^15 = 9.4608 x 10^25 m

Answer:  

more than 10 billion light years due to expansion of space

Explanation:

Find answers and explanations in the attachments

Answer:

Explanation:

) (C) Suppose the piston is fixed. Find the energy input required to raise the temperature to 700 K.

Answer:

t = 160 minutes

Explanation:

Given that,

Distance of Uranus from Sun is [tex]2.88\times 10^9\ km[/tex]

We need to find the time taken by the light to go from sun to Uranus if the velocity of light is constant in free space and it is equal to c.

So,

[tex]t=\dfrac{d}{v}\\\\t=\dfrac{2.88\times 10^9\times 10^3\ m}{3\times 10^8}\\\\t=9600\ s[/tex]

Since, 1 minute = 60 seconds

t = 160 minutes

So, 160 minutes is taken by the light.

Answer:

Three

Explanation:

I hope this helps:)

Answer:

what do u need help with

Explanation:

A body of mass m moves along X-axis such that its position co-ordiante at any instant t is x = `at^(4)

Answer:

I think no because the critical properties distinguishing life is adaptation to changing environment and self replication of the information encoding the life process. Fire does not change its process to adapt to its environment, e.g. moving toward more fuel or storing and conserving fuel when it is in short supply.

Hope this help you!:)

Answer:

50m/s.

Explanation:

Let's take acceleration as A and speed as S:

A = 5m/s²

S = A × 10s = 5 × 10 = 50m/s

The answer is 50m/s.

Answer:

50m/s

Explanation:

Given:

a=5m/s^2

t=10s

Required:

v=?

Formula:

a=v/t

Solution:

a=v/t

v=a*t

v=5m/s^2*10s

v=50m/s

Hope this helps ;)❤❤❤

Answer:

The comparison of unknown quantity with known quantity is called measurement

Answer:

the size, length or amount of something is a measurement.

Explanation:

Measurements help in daily life and are important to development, accuracy and making decisions.

Oil is optically denser than water. When sound/light goes from optically denser medium to optically rarer medium, their velocity increase and they moves away for normal.

The sound wave speeds up and bends

[tex] \Large{ \underline{ \boxed{ \pink{ \bf{Option \: (D)}}}}}[/tex]

As, In optics we learnt that light undergoes refraction when travels from medium of different densities. Similarly, Sound also follows the law of refraction.

━━━━━━━━━━━━━━━━━━━━

Answer:

the sound wave slows down and bends

Explanation:

a p e x

Answer:

66.86m

Explanation:

Velocity of ball thrown, u = 23.5 m/s

Initial height of the ball above the water, H = 11.5 m

Angle of projection, θ = 39.5°

Vertical components of veloclty = usinθ

Horizontal components of veloclty = ucosθ

The soft ball hits the water after time 't'

Considering the second equation of motion

S = ut + 1/2at^2........ 1

But since the ball went through motion under gravity ( free fall ) rather than linear motion, then equation 1 can be rewritten as:

H = ut +/- 1/2gt^2

H = - 11.5m

U = usinθ

θ = 39.5°

a = -g = -9.8m/s^2

- 11.5m = 23.5(sin39.5°)t + 1/2(-9.8)t^2

-11.5m = 23.5(0.6360)t - 4.9t^2

-11.5m = 14.946t - 4.9t^2

4.9t^2 -14.946t-11.5m = 0

Since the ball drifted horizontally

D = (Ucosθ)t

Where θ = 39.5°

U = 23.5m/s t=

Alternatively,

horizontal component of the velocity is 23.5 cos 39.5º = 18.1331 m/s

now how long does it take the ball to raise to a peak and fall to the water.

vertical component of velocity = 23.5 sin 39.5º = 14.947m/s

time to reach peak t = v/g = 11.947/9.8 = 1.5252 sec

peak reached above cliff top is

h = ½gt² = ½(9.8)(1.5252)²

= ½×22.797

= 11.3985m

now the ball has to fall 11.3985+ 11.5 = 22.8985m

time to fall from that height is

t = √(2h/g) = √(2• 22.8986/9.8) = 2.1617 sec

add up the two times to get time it is in the air, 2.1617 + 1.5252 = 3.6869

now haw far does the ball travel horizontally in that time

d = vt = 18.1331 ×3.6869= 66.856m

= 66.86m

Answer:

20 N

Explanation:

In air, the normal force is equal to the weight.

∑F = ma

N − mg = 0

N = mg

Submerged in water, the normal force is equal to the weight minus the buoyant force:

∑F = ma

B + N − mg = 0

N = mg − B

Plugging in values:

80 N = 100 N − B

B = 20 N

Answer:

Explanation: pressure = force / area

Rearrange to get: force = pressure x area. 900 cm2 = 0.09 m2

force = 90 x 0.09

= 8.1 N

Answer:

a) La magnitud del desplazamiento es de 5 m

La magnitud de la fuerza es 20 N

b) El trabajo realizado por la fuerza es de 100 J

c) El ángulo entre la fuerza y el plano es 0 °

Explanation:

a) La magnitud del desplazamiento se encuentra por la relación;

[tex]\left | X \right | = \sqrt{X_{x}^{2}+X_{y}^{2}}[/tex]

Lo que da;

[tex]\left | X \right | = \sqrt{4^{2}+3^{2}} = 5 \ m[/tex]

De manera similar, la magnitud de la fuerza, F, se encuentra como sigue;

[tex]\left | F \right | = \sqrt{F_{x}^{2}+F_{y}^{2}}[/tex]

Lo que da;

[tex]\left | F \right | = \sqrt{16^{2}+12^{2}} = 20 \ N[/tex]

b) El trabajo, W, realizado por la fuerza = Fuerza, F × Distancia, X

∴ Ancho = 20 N × 5 m = 100 N · m = 100 J

c) La dirección de la fuerza viene dada por la siguiente fórmula;

[tex]tan^{-1} \left (\dfrac{F_y}{F_x} \right ) = tan^{-1} \left (\dfrac{12}{16} \right ) = 38.9^{\circ}[/tex]

La dirección del plano viene dada por la siguiente fórmula;

[tex]tan^{-1} \left (\dfrac{X_y}{X_x} \right ) = tan^{-1} \left (\dfrac{3}{4} \right ) = 38.9^{\circ}[/tex]

Por tanto, el ángulo entre la fuerza y el plano = 0 °

La fuerza actúa a lo largo del plano.

Answer:

-40

Explanation:

-40= (9/5)(-40) + 32

=-72 + 32

-40=-40

Answer:

for students to do nothing

Explanation:

because doing nothing is not a course goal

The magnitude (size or numerical value) and the direction.

Hope this helps!!! :)

Explanation:

If a coil of wire is placed in a changing magnetic field, a current will be induced in the wire. ... A changing magnetic field through a coil of wire therefore must induce an emf in the coil which in turn causes current to flow.

Due to the flow of the current run, the coil magnetic field is produced. Magnetic fields result in magnetic force.

The electric force between the two charges is directly propotional to the product of the charge and inversly propotional to the square of the distance between them.

A current will be generated in a wire coil if it is put in a changing magnetic field. As a result, a changing magnetic field through a coil of wire must create an emf in the coil, causing the current to flow.

A current is induced in a coil of wire when it is put in a changing magnetic field. Something generates an electric field that drives the charges around the wire, causing the current to flow.

Hence due to the flow of the current in the coil magnetic field is produced.

To learn more about the electric force refer to the link;

https://brainly.com/question/1076352

Answer:

Option D (Electricity can flow through it under special conditions ) seems to be the correct choice.

Explanation:

Other options that are provided are not related to the given theory. So that the above would be the correct choice.

Statement "Lack free electrons that can move to other atoms " describe semi-conductor.

Learn  more about the Semiconductor here:

https://brainly.com/question/1918629

Answer:

940 nanometers wavelength, and about an 300 mHz - 400 gHz frequency

Answer:

Pressure

Explanation:

One of the theories propounded by the Kinetic molecular theory, and which also provides an explanation of the several gas laws, is the statement that the gas molecules in a container, travel in straight lines and are in constant collision with themselves and the walls of the container, thus exerting force. This force is the pressure which is defined as the force per unit area.

There is no loss of energy in the collisions involving the gas molecules and that is why their movement can be described as elastic. The descriptions of the behavior of gas molecules in the Kinetic Molecular Theory, give rise to Charles law, Boyle's Law, Avogadro's Laws, Dalton's Law, and Amonton's Law.

Answer:

The pressure

Explanation:

Molecules of gases are constantly in motion, colliding with the walls of their container. This constant collision impacts force on the walls of the container, which depends on the speed with which the molecules are moving. The speed with which these molecules travel depends on the average kinetic energy of the molecules, which is proportional to the temperature.

This force when exerted per unit area is the pressure the gases exert on the walls of the container.

Answer:

Explanation:

Evolution/Advancement on the off chance that you see,then you will find this is a definitive revelation of science.It demonstrated that how people came into the world.How different creatures endure and from where they have hit on where they are today.All such things are the piece of development process.

New things advanced consistently from the past one and its a slow process.For anything to sprout you need a seed.As per the scientist,evolution is a reality and it is a steady procedure and it is happening.There are scarcely any situations where in the old harvest can yield new assortment as well.This is something many refer to as advancement only.Its a ceaseless process.Whatever comes,it accompanies certain misstep or zones of improvement,so if there happens to be a few changes would prompt improvement of new thing.

In the event that you see at an early stage,worms were available ,from where the fish came,then some went ahead land and began adjusting the progressions require to make due on land,started strolling on legs,developed lungs,then likewise there were advancement of the considerable number of things require to proceed with the life.All are the piece of development as it were.

hence,Darwin said,that natural selection can prompt evolution.This is likewise evident that so as to address the issue of food and nutrition,everybody works and as long as you get those needs,there will be development in all aspects.Similarly happened to the antiquated occasions when advancement occurred.

Hence,The development is truth and is a continuous procedure according to the science.When you go to demonstrate some case,there are consistently a point from where new methodology can be shaped and can prompt another disclosure.

If we consider the theory of evolution then we can say that it’s a proven theory, the reason people says that scientists don’t prove anything is because of the fact that they always implement “Precautionary principle” in their research finding.

Answer:

.

Explanation:

Answer:

the rock will sink. this is because it is more dense than water

Answer:it will sink

Explanation:

because the density of water is 1g and the rock is heavier the the density of water

Answer:

Metals (like copper and aluminium) are good conductors of heat and electricity, while nonmetals (such as phosphorus and sulfur) are insulators.

Explanation:

i don't really have one i just know

Answer:

1 of them is metel and one is not

Explanation:

Answer:

Scattering of light is the phenomenon in which light rays get deviated from its straight path on striking an obstacle like dust or gas molecules, water vapours etc. Scattering of light gives rise to many spectacular phenomena such as Tyndall effect and the “red hues of sunrise and sunset”.

Answer:

0.699 L of the fluid will overflow

Explanation:

We know that the change in volume ΔV = V₀β(T₂ - T₁) where V₀ = volume of radiator = 21.1 L, β = coefficient of volume expansion of fluid = 400 × 10⁻⁶/°C

and T₁ = initial temperature of radiator = 12.2°C and T₂ = final temperature of radiator = 95.0°C

Substituting these values into the equation, we have

ΔV = V₀β(T₂ - T₁)

= 21.1 L × 400 × 10⁻⁶/°C × (95.0°C - 12.2°C)

= 21.1 L × 400 × 10⁻⁶/°C × 82.8°C = 698832 × 10⁻⁶ L

= 0.698832 L

≅ 0.699 L = 0.7 L to the nearest tenth litre

So, 0.699 L of the fluid will overflow

Answer:

Final velocity = 119.83 m/s

Final elevation = 731.9 m

Explanation:

We are told that temperature of air changes from 0 to 10°C

Thus;

Change in temperature; ΔT = 10 - 0 = 10°C

Also, its velocity changes from zero to a final velocity. Thus;

v1 = 0 m/s

v2 is unknown

Also, its elevation changes from zero to a final elevation.

So, z1 = 0 and z2 is unknown

Now, we want to find v2 and z2 when the internal, kinetic and potential energy are equal.

Thus Equating the formula for both kinetic and internal energy gives;

½m(v2² - v1²) = mc_v•ΔT

m will cancel out and v1 is zero to give;

v2² = 2c_v•ΔT

v2 = √(2c_v•ΔT)

Where c_v is specific heat of constant volume of air with a constant value of 718 J/Kg.K

Thus;

v2 = √(2 × 718 × 10)

v2 = √14360

v2 = 119.83 m/s

To find z2, we will equate potential energy formula to that of the internal energy.

Thus;

mg(z2 - z1) = mc_v•ΔT

m will cancel out and since z1 is zero, then we have;

z2 = (c_v•ΔT)/g

z2 = 718 × 10/9.81

z2 = 731.9 m

Answer:

Furthermore, the Pythagorean theorem works when the two added vectors are at right angles to one another - such as for adding a north vector and an east vector.