Silicon is lustrous and is a conductor of heat and electricity. Which class of elements could this element belong to?

What is hypothesis please help

Mama L [17]

A hypothesis is how you think the experiment is going to end

5 0

3 years ago

Read 2 more answers

Match each element to the number of electrons in its valence shell.

irinina [24]

Answer:

C: 4

H: 1

Mg: 2

O : 6

Explanation:

You can quickly find out the number of valence electrons by looking at where the element is on the periodic table and referring to the table that is attached.

6 0

1 year ago

Carbon-14 is a radioactive isotope that decays according to first-order kinetics in a process that has a half-life of 5730 years

Sliva [168]

Answer : The time passed in years is $2.83\times 10^3\text{ years}$

Explanation :

Half-life = 5730 years

First we have to calculate the rate constant, we use the formula :

$k=\frac{0.693}{t_{1/2}}$

$k=\frac{0.693}{5730\text{ years}}$

$k=1.21\times 10^{-4}\text{ years}^{-1}$

Now we have to calculate the time passed.

Expression for rate law for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant = $1.21\times 10^{-4}\text{ years}^{-1}$

t = time passed by the sample = ?

a = let initial amount of the reactant = X g

a - x = amount left after decay process = $71\% \times (x)=\frac{71}{100}\times (X)=0.71Xg$

Now put all the given values in above equation, we get

$t=\frac{2.303}{1.21\times 10^{-4}}\log\frac{X}{0.71X}$

$t=2831.00\text{ years}=2.83\times 10^3\text{ years}$

Therefore, the time passed in years is $2.83\times 10^3\text{ years}$

8 0

3 years ago

Is a hollow tube that serves as passageway of air into the luns

KIM [24]

Answer:

The air that we breathe in enters the nose or mouth, flows through the throat (pharynx) and voice box (larynx) and enters the windpipe (trachea). The trachea divides into two hollow tubes called bronchi

Explanation:

7 0

3 years ago

How many helium atoms are there in a helium blimp containing 536 kg of helium? n = atoms?

Mariulka [41]

Answer:- $8.07*10^2^8atoms$

Solution:- It is a unit conversion where it asks to convert kg of He to atoms. We need to convert kg to grams, grams to moles and finally moles to atoms.

We know that, 1 kg = 1000 g

Molar mass of He is 4.0 grams per mole and 1 mole of an atom equals to Avogadro number of atoms.

The set up would be as given below:

$536kg(\frac{1000g}{1kg})(\frac{1mole}{4g})(\frac{6.02*10^2^3atoms}{1mole})$

= $8.07*10^2^8atoms$

So, there are $8.07*10^2^8atoms$ of He in it's 536 kg.

5 0

4 years ago