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3 years ago

Elements in the same group have similar properties because they

Physics

1 answer:

MA_775_DIABLO [31]3 years ago

4 0

Answer: A. need the same number of electrons to fill their valence shells

B. have the same number of valence electrons

Explanation:

Elements are distributed in groups and periods in a periodic table.

Elements that belong to same groups will show similar chemical properties because they have same number of valence electrons.

Example: Flourine, chlorine and bromine are elements which belong to Group 17. They have 9, 17 and 35 electrons respectively and contain 7 valence electrons each and need one electron to complete their octet.

The chemical reactivity of elements is governed by the valence electrons present in the element.

$F:9:1s^22s^22p^5$

$Cl:17:1s^22s^22p^63s^23p^5$

$Br:35:1s^22s^22p^63s^23p^63d^{10}4s^24p^5$

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A 12 g plastic ball is dropped from a height of 2.5 m and is moving at 3.2 m/s just before it hits the floor. How much mechanica

Nataly [62]

Answer:

0.24

Explanation:

Mass of ball= 12g=0.012Kg

height of ball= 2.5m

velocity of ball before falling= 3.2m/s

potential energy of the ball=mgh= 0.012*10*2.5=0.3J

kinetic energy of the ball=0.5*m $v^{2}$ =0.5*0.012*3.2*3.2=0.6J

Loss in mechanical energy during the fall= potential energy- Kinetic energy= 0.3-0.06=0.24J

note: During the fall, the potential energy of the ball is converted to kinetic energy. the loss in energy is due to air resistance.

4 0

3 years ago

20. A 0.145 kg mass of tungsten at 130.0 °C is placed in a 0.502 kg of water at 22.0 °C. The mixture reaches equilibrium at 28.6

zepelin [54]

MaCa∆Tb = MbC∆Tb
Where m is the mass of a compound
 C is the specific heat of a compound
∆T is the change of temperature of the compound
 (0.502 kg water)(4180 j/kg C)( 28.6 – 22 C) = ( 0.145 kg tungsten) ( C ) ( 130 – 28.6 C)
Solve for C
C = 941.9 J /kg C

8 0

3 years ago

Three resistors of 4.0, 6.0, and 10.0 Ω are connected in parallel. If the combination is connected in series with a 12.0-V batte

Grace [21]

Answer:

0.536 A

Explanation:

From the question,

The combined resistance of the parallel connection is given as

1/Rt = 1/4+1/6+1/10

Rt = 120/15

Rt = 8 ohms.

Since the the combination is connected in series with a 10 ohms resistor,

Rt' = 8+10 = 18 ohms.

Current flowing through the series circuit

I = V/Rt'

V = 12 V, Rt' = 18 ohms

I = 12/18

I = 0.67 A.

Therefore voltage across the combined resistor

V' = 8(0.67)

v' = 5.36 V.

Since the resistors a connected in parallel, the same voltage drop across them.

Therefore, current through the 10 ohms

Ix = 5.36/10

Ix = 0.536 A

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3 years ago

What is the average speed of a commercial jet that travels from New York to Los Angeles 4800 kilometer in six hours

Alex Ar [27]

Answer: 800 km/h

Explanation:

Use equation for average speed

V=S/t

where S is distance

t is time

S=4800Km

t=6h

---------

V=S/t

V=4800Km/6h=800 Km/h

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4 years ago

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Delvig [45]

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3 years ago