At the other extreme, a 10 M solution of NaOH would have a pH of 15. Numerical examples from Shipman, Wilson and Todd. In pure water, the molar concentration of H + ions is 10-7 M and the concentration of OH-ions is also 10-7 M.
In order to tell if a guava is ripe, squeeze it gently. If it gives under your fingers, its ripe. 2. Look for any blemishes on the guava. You want to try to select guavas that are blemish-free. Blemishes or bruises can mean the fruit is bad or will not taste good. 3. Check the color of the guava. Ripe guavas are those that have gone from bright green to a softer yellowish-green color. If you see a touch of pink on the fruit, it is in its prime. If you don't find any that are yellow, you can always buy green guava and wait for them to ripen.
1 Place green guavas in a paper bag with a banana or apple for faster ripening. 2  A large crop of guavas can be kept for two to four weeks in a cool, moist environment -- temperature from 46 to 50 degrees Fahrenheit and humidity from 80 to 95 percent -- if picked when mature but still green. Ripe guavas can be stored in the refrigerator for two days. 2  Guavas purchased or picked when green and hard continue to ripen when kept at room temperature. 3  Place green guavas in a paper bag with a banana or apple for faster ripening.