Answer:
12:7
Explanation:
To Determine: To calculate the formula of the unknown binary compound of oxygen and nitrogen and to ratio in the next compound of the series using given data.Answer:The formula of the unknown compound .The ratio for atoms of oxygen to nitrogen inis .The mass ratio of oxygen to nitrogen in next member of the series of compounds is .Explanation:The mass ratio of toinis .The mass ratio of toin theunknown compound is .The atomic mass of the oxygen is .The atomic mass of the nitrogen is .The mass ratio of to in a molecule can be represented as: …… (1)Here,is the number of atoms of the oxygen in the molecule.is the mass of an atom of oxygen.is the number of atoms of the nitrogen in the molecule.is the mass of an atom of nitrogen.For unknown compound, substitutefor , for and for mass ratio in equation (1).The ratio of atoms of oxygen to nitrogen is , therefore, the expected formulas of the unknown compound is and . If the unknown compound is in a series with then the formula of the unknown compound and the formula for the next member of the series is .The ratio for atoms of oxygen to nitrogen inis .For , substitute 5 for , for , 2 for and for in equation (1).The mass ratio of oxygen to nitrogen in next member of the series of the compounds is .
The heat lost is 
The heat lost when the ice is cooled from 400k to 263K can be calculated using the formula of heat transfer.
<h3>Heat Transfer</h3>
This is the heat transferred from a body of higher temperature to a body of lower temperature.

- Q = Heat Transfer
- m = mass = 1277g
- ΔT = change in temperature

We converted the temperature from kelvin scale into Celsius scale and find the change in temperature.
Solving for heat transfer

The heat loss is approximately 
Learn more on heat transfer here;
brainly.com/question/16055406
Answer:
T =76.13 K
Explanation:
Given data:
Temperature of gas = ?
Volume of gas = 250 mL(250/1000 = 0.25 L)
Mass of helium = 0.40 g
Pressure of gas = 253.25 kpa (253.25/101 = 2.5 atm)
Solution:
Formula:
PV = nRT
First of all we will determine the number of moles of helium.
Number of moles = mass/ molar mass
Number of moles = 0.40 g/ 4 g/mol
Number of moles = 0.1 mol
Now we will put the values.
R = general gas constant = 0.0821 atm.L/ mol.K
T = PV/nR
T =2.5 atm× 0.25 L /0.1 mol ×0.0821 atm.L/ mol.K
T = 0.625 /0.00821/K
T =76.13 K
The reason why Tin granules is mostly used or preferred than
just a piece of Tin because a piece of Tin is plainly metal, in which this will
be difficult in having it to be oxidized when it is exposed or in the air
rather than Tin granules.
<u>Answer:</u> The volume of stock solution of calcium chloride required is 10 mL.
<u>Explanation:</u>
A solution consists of solute and solvent. A solute is defined as the component that is present in a smaller proportion while the solvent is defined as the component that is present in a larger proportion.
To calculate the amount of solute needed, the formula used is:
....(1)
where,
are the concentration and volume of stock solution of calcium chloride
are the concentration and volume of diluted solution of calcium chloride
Given values:

Plugging values in equation 1:

Hence, the volume of stock solution of calcium chloride required is 10 mL.