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2 years ago

Hãy so sánh và sắp xếp theo chiều tăng dần tính kim loại của các nguyên tố sau: a) Al, Na,Mg, Si

Chemistry

1 answer:

Alchen [17]2 years ago

7 0

$\huge\underline\mathtt\colorbox{cyan}{Na>Mg>Al>Si}$

Answer is verfied, trust me!

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The half-life of cesium-134 is 2.06 years. If you start with 24 atoms of

emmainna [20.7K]

Number of atoms of Cesium-134 left = 12 atoms

<h3>Further explanation </h3>

The atomic nucleus can experience decay into 2 particles or more due to the instability of its atomic nucleus.

Usually radioactive elements have an unstable atomic nucleus.

The main particles are emitted by radioactive elements so that they generally decay are alpha (α), beta (β) and gamma (γ) particles

General formulas used in decay:

$\large{\boxed{\bold{N_t=N_0(\dfrac{1}{2})^{t/t\frac{1}{2} }}}$

t = duration of decay

t 1/2 = half-life

N₀ = the number of initial radioactive atoms

Nt = the number of radioactive atoms left after decaying during T time

No=24 atoms

t1/2=2.06 years

T=2.06 years = t1/2

Since the decay time is the same as the half-life time, the number of atoms of Cesium-134 will be halved from 24 to 12.

Or we can use the formula above

$\tt Nt=24\times \dfrac{1}{2}^{2.06/2.06}\\\\Nt=24\times \dfrac{1}{2}=12$

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3 years ago

What is the total number of moles of hydrogen atoms contained in 1 mole of (nh42c2o4?

skad [1K]

The answer is 8. Hope this helps.

3 0

3 years ago

Calculate the final temperature of 35 mL of ethanol initially at 20 ∘C upon absorption of 720 J of heat. (density of ethanol =0.

Natalija [7]

The specific heat capacity of ethanol is 2.46 joules per gram.
Now, we may use the equation:
Energy = mass * specific heat capacity * change in temperature

Here we may substitute:
mass = density * volume

Energy = density * volume * specific heat capacity * change in temperature
720 = 0.789 * 35 * 2.46 * ΔT
ΔT = 10.6

The final temperature will be
20 + 10.6
= 30.6 °C

4 0

4 years ago

Determine molar mass of Mn (ClO3)3

goldenfox [79]

M(Mn(ClO3)3)=(54.938)+(35.45x3)+(15.999x9)
M(Mn(ClO3)3)=305.279 g/mol

8 0

3 years ago

The substances below are listed by increasing specific heat capacity value. Starting at 30 Celsius, they absorb 100 kJ of therma

Georgia [21]

Answer:

Silver.

Explanation:

To obtain the right answer to question, let us calculate the change in temperature for each substance assuming they all have the same mass as 100g.

This is illustrated below:

1. For Siver:

Mass (M) = 100g

Specific heat capacity (C) = 0.239J/g°C

Heat (Q) = 100 kJ = 100000J

Change in temperature (ΔT)

Q = MCΔT

ΔT = Q/MC

ΔT = 100000/(100 x 0.239)

ΔT = 4184°C

2. For Aluminium:

Mass (M) = 100g

Specific heat capacity (C) = 0.921J/g°C

Heat (Q) = 100 kJ = 100000J

Change in temperature (ΔT)

Q = MCΔT

ΔT = Q/MC

ΔT = 100000/(100 x 0.921)

ΔT = 1086°C

3. For Lithium:

Mass (M) = 100g

Specific heat capacity (C) = 3.56J/g°C

Heat (Q) = 100 kJ = 100000J

Change in temperature (ΔT)

Q = MCΔT

ΔT = Q/MC

ΔT = 100000/(100 x 3.56 )

ΔT = 281°C

4. For water:

Mass (M) = 100g

Specific heat capacity (C) = 4.184J/g°C

Heat (Q) = 100 kJ = 100000J

Change in temperature (ΔT)

Q = MCΔT

ΔT = Q/MC

ΔT = 100000/(100 x 4.184)

ΔT = 239°C

Summary

Temperature change of each substance is given below

1. Silver => 4184°C

2. Aluminum => 1086°C

3. Lithium => 281°C

4. Water => 239°C

From the calculations made above, Silver has the highest rise in temperature.

4 0

4 years ago