1. What mass of Mgo will I make from 48 g of Mg? 2Mg + O2 + 2MgO

How many atoms of hydrogen are present in 7.63 g of ammonia? please help me ??

GarryVolchara [31]

The atoms of hydrogen that are present in 7.63 g of ammonia(NH3)

find the moles of NH3 =mass/molar mass
7.63 g/ 17 g/mol = 0.449 moles

since there is 3 atoms of H in NH3 the moles of H = 0.449 x 3 = 1.347 moles

by use of 1 mole = 6.02 x10^23 atoms
what about 1.347 moles

= 1.347 moles/1 moles x 6.02 x10^23 atoms = 8.11 x10^23 atoms of Hydrogen

3 0

3 years ago

HELP PLEASEEEEEEEE HELPPPPPPP (IMAGE)

lapo4ka [179]

1. Liquid
2. Gas
3. Solid

5 0

3 years ago

What is the law of fossil succession?:

nata0808 [166]

Different Fossil organisms succeed one another to go up through the different rock layers in a definite and determinable order. Therefore, any time period can be recognized by its fossil content

Explanation:

Different Fossil organisms succeed one another to go up through the different rock layers in a definite and determinable order. Therefore, any time period can be recognized by its fossil content

3 0

2 years ago

Please Help!

Whitepunk [10]

We can use two equations for this problem.

t1/2 = ln 2 / λ = 0.693 / λ
Where t1/2 is the half-life of the element and λ is decay constant.

20 days = 0.693 / λ
λ = 0.693 / 20 days (1)

Nt = Nο eΛ(-λt) (2)

Where Nt is atoms at t time, No is the initial amount of substance, λ is decay constant and t is the time taken.
t = 40 days

No = 200 g

From (1) and (2),
Nt = 200 g eΛ(-(0.693 / 20 days) 40 days)
Nt = 50.01 g

Hence, 50.01 grams of isotope will remain after 40 days.

3 0

3 years ago

Many monatomic ions are found in seawater, including the ions formed from the following list of elements. Write the Lewis symbol

77julia77 [94]

Answer:

The Lewis structures are in image attached.

Explanation:

Lewis symbol is a representation of an element symbol along with its valence electrons around it in the form of dot(s).

Mono-atomic ions formed from the following :

(a) Cl

Chlorine's atomic number is 17 in which only 7 electrons are present in its valence shell .So in order to gain noble gas stability it will gain 1 electron to completes its octet

$Cl=1s^22s^22p^63s^23p^5$

$Cl^-=1s^22s^22p^63s^23p^6$

(b) Na

Sodium's atomic number is 11 in which only 1 electrons are present in its valence shell .So in order to gain noble gas stability it will loose 1 electron to completes its octet. In the Lewis symbol no dot shown as sodium has lost its 1 electron.

$Na=1s^22s^23p^63s^1$

$Na^+=1s^22s^23p^63s^0$

(c) Mg

Magnesium's atomic number is 12 in which only 2 electrons are present in its valence shell .So, in order to gain noble gas stability it will loose 2 electrons to completes its octet.

In the Lewis symbol no dot shown as magnesium has lost its 2 electrons.

$Mg=1s^22s^23p^63s^2$

$Mg^{2+}=1s^22s^23p^63s^0$

(d)Ca

Calcium's atomic number is 20 in which only 2 electrons are present in its valence shell .So, in order to gain noble gas stability it will loose 2 electron to completes its octet.

In the Lewis symbol no dot shown as calcium has lost its 2 electron.

$Ca= 1s^22s^22p^63s^23p^64s^2$

$Ca^{2+}=1s^22s^23p^6^23p^64s^0$

(e) K

Potassium's atomic number is 19 in which only 1 electrons are present in its valence shell .So, in order to gain noble gas stability it will loose 1 electron to completes its octet.

In the Lewis symbol no dot shown as calcium has lost its 1 electron.

$K= 1s^22s^22p^63s^23p^64s^1$

$K^{+}=1s^22s^23p^6^23p^64s^0$

(f) Br

Bromine's atomic number is 35 in which only 7 electrons are present in its valence shell .So in order to gain noble gas stability it will gain 1 electron to completes its octet

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

$Br^-= 1s^22s^22p^63s^23p^63d^{10}4s^24p^6$

(g) Sr

Strontium's atomic number is 38 in which only 2 electrons are present in its valence shell .So, in order to gain noble gas stability it will loose 2 electron to completes its octet.

In the Lewis symbol no dot shown as calcium has lost its 2 electron.

$Sr=1s^22s^22p^63s^23p^63d^{10}4s^24p^65s^2$

$Sr^{2+}=1s^22s^22p^63s^23p^63d^{10}4s^24p^65s^0$

(h) F

Florine's atomic number is 7 in which only 7 electrons are present in its valence shell .So in order to gain noble gas stability it will gain 1 electron to completes its octet.

$F=1s^22s^22p^5$

$F^-=1s^22s^22p^6$

5 0

3 years ago