Answer:
can u tell the question in english
The two ways to measure the sand in a sand castle are by counting the number of pails of sand used to build the castle and by determining the mass of the sand used in building the castle. The first method makes use of the volume of the pail to determine the amount of sand while the second method is a more quantitative way.<span />
Chemical property is the property of the substances that describes the ability of the substance to involve in chemical reactions. Physical property is that which does not change the chemical composition of the substances. The following properties of water that it is transparent and tasteless in its pure form and it freezes at a temperature of 
are physical properties as they simply indicate the change in physical state without any change in chemical composition of water.
The other two properties that water reacts with halogens to form oxygen gas as one of the products and water decomposes to form hydrogen and oxygen are chemical properties as the chemical composition of water changes in the given reaction.
Therefore the correct answer is b. 1 and 4
A single sodium ion will combine due to its charge on it
Na^+
The single sodium ion has total one positive charge on it. so it requires only one electron or can bond to one negative charge
in the given polyatomic anions
a) CO3^-2 : it has two negative charge. So it will react with two sodium ions
it will forms Na2CO3
b) PO4^-3 :it has three negative charge. So it will react with three sodium ions
it will forms Na3PO4
c) SO4^-2 : it has two negative charge. So it will react with two sodium ions
it will forms Na2SO4
d) NO3^-1: it has one negative charge. So it will react with one sodium ion
it will forms NaNO3
Hence the correct answer is
Nitrate ion will react with single sodium ion as
Na+ + NO3- ---> NaNO3
